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Water collected between towers: Difference between revisions
uBasic/4tH - eliminated a global
(Added vb.Net program, features erosion of strings method instead of tower height comparison method,) |
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Line 8:
<pre>9 ██ 9 ██
8 ██ 8 ██
7 ██ ██ 7
6 ██ ██ ██ 6
5 ██ ██ ██ ████ 5
4 ██ ██ ████████ 4
3 ██████ ████████ 3
2 ████████████████ ██ 2
1 ████████████████████ 1 ████████████████████</pre>
Line 40:
<br>
=={{header|11l}}==
{{trans|Python}}
<syntaxhighlight lang="11l">F water_collected(tower)
V l = tower.len
V highest_left = [0] [+] (1 .< l).map(n -> max(@tower[0 .< n]))
V highest_right = (1 .< l).map(n -> max(@tower[n .< @l])) [+] [0]
V water_level = (0 .< l).map(n -> max(min(@highest_left[n], @highest_right[n]) - @tower[n], 0))
print(‘highest_left: ’highest_left)
print(‘highest_right: ’highest_right)
print(‘water_level: ’water_level)
print(‘tower_level: ’tower)
print(‘total_water: ’sum(water_level))
print(‘’)
R sum(water_level)
V towers = [
[1, 5, 3, 7, 2],
[5, 3, 7, 2, 6, 4, 5, 9, 1, 2],
[2, 6, 3, 5, 2, 8, 1, 4, 2, 2, 5, 3, 5, 7, 4, 1],
[5, 5, 5, 5],
[5, 6, 7, 8],
[8, 7, 7, 6],
[6, 7, 10, 7, 6]]
print(towers.map(tower -> water_collected(tower)))</syntaxhighlight>
{{out}}
<pre>
highest_left: [0, 1, 5, 5, 7]
highest_right: [7, 7, 7, 2, 0]
water_level: [0, 0, 2, 0, 0]
tower_level: [1, 5, 3, 7, 2]
total_water: 2
highest_left: [0, 5, 5, 7, 7, 7, 7, 7, 9, 9]
highest_right: [9, 9, 9, 9, 9, 9, 9, 2, 2, 0]
water_level: [0, 2, 0, 5, 1, 3, 2, 0, 1, 0]
tower_level: [5, 3, 7, 2, 6, 4, 5, 9, 1, 2]
total_water: 14
...
highest_left: [0, 6, 7, 10, 10]
highest_right: [10, 10, 7, 6, 0]
water_level: [0, 0, 0, 0, 0]
tower_level: [6, 7, 10, 7, 6]
total_water: 0
[2, 14, 35, 0, 0, 0, 0]
</pre>
=={{header|8080 Assembly}}==
<syntaxhighlight lang="8080asm"> org 100h
jmp demo
;;; Calculate the amount of water a row of towers will hold
;;; Note: this will destroy the input array.
;;; Input: DE = tower array, BC = length of array
;;; Output: A = amount of water
water: xra a ; Start with no water
sta w_out+1
wscanr: mov h,d ; HL = right edge
mov l,e
dad b
wscrlp: dcx h
call cmp16 ; Reached beginning?
jnc w_out ; Then stop
mov a,m ; Otherwise, if current tower is zero
ora a
jz wscrlp ; Then keep scanning
push b ; Keep length
push d ; Keep array begin
mvi b,0 ; No blocks yet
xchg ; HL = left scanning edge, DE = right
wscanl: mov a,m ; Get current column
ora a ; Is zero?
jz wunit ; Then see if an unit of water must be added
dcr m ; Otherwise, decrease column
inr b ; Increase blocks
jmp wnext
wunit: mov a,b ; Any blocks?
ora a
jz wnext
lda w_out+1 ; If so, add water
inr a
sta w_out+1
wnext: inx h ; Next column
call cmp16
jnc wscanl ; Until right edge reached
mov a,b
cmc ; Check if more than 1 block left
rar
ora a
pop d ; Restore array begin
pop b ; and length
jnz wscanr ; If more than 1 block, keep scanning
w_out: mvi a,0 ; Load water into A
ret
;;; 16-bit compare DE to HL
cmp16: mov a,d
cmp h
rnz
mov a,e
cmp l
ret
;;; Calculate and print the amount of water for each input
demo: lxi h,series
load: mov e,m ; Load pointer
inx h
mov d,m
inx h
mov c,m ; Load length
inx h
mov b,m
inx h
mov a,d ; If pointer is zero,
ora e
rz ; stop.
push h ; Otherwise, save the series pointer
call water ; Calculate amount of water
call printa ; Output amount of water
pop h ; Restore series pointer
jmp load ; Load next example
;;; Print A as integer value
printa: lxi d,num ; Pointer to number string
mvi c,10 ; Divisor
digit: mvi b,-1 ; Quotient
dloop: inr b ; Divide (by trial subtraction)
sub c
jnc dloop
adi '0'+10 ; ASCII digit from remainder
dcx d ; Store ASCII digit
stax d
mov a,b ; Continue with quotient
ana a ; If not zero
jnz digit
mvi c,9 ; 9 = CP/M print string syscall
jmp 5 ; Print number string
db '***' ; Output number placeholder
num: db ' $'
;;; Series
t1: db 1,5,3,7,2
t2: db 5,3,7,2,6,4,5,9,1,2
t3: db 2,6,3,5,2,8,1,4,2,2,5,3,5,7,4,1
t4: db 5,5,5,5
t5: db 5,6,7,8
t6: db 8,7,7,6
t7: db 6,7,10,7,6
t_end: equ $
;;; Lengths and pointers
series: dw t1,t2-t1
dw t2,t3-t2
dw t3,t4-t3
dw t4,t5-t4
dw t5,t6-t5
dw t6,t7-t6
dw t7,t_end-t7
dw 0</syntaxhighlight>
{{out}}
<pre>2 14 35 0 0 0 0</pre>
=={{header|8086 Assembly}}==
<syntaxhighlight lang="asm"> cpu 8086
org 100h
section .text
jmp demo
;;; Calculate the amount of water a row of towers will hold
;;; Note: this will destroy the input array.
;;; Input: DX = tower array, CX = length of array
;;; Output: AX = amount of water
water: xor ax,ax ; Amount of water starts at zero
xor bx,bx ; BH = zero, BL = block count
.scanr: mov di,dx ; DI = right edge of towers
add di,cx
.rloop: dec di
cmp di,dx ; Reached beginning?
jl .out ; Then calculation is done.
cmp bh,[di] ; Otherwise, if the tower is zero,
je .rloop ; Keep scanning
xor bl,bl ; Set block count to zero
mov si,dx ; SI = left scanning edge
.scanl: cmp bh,[si] ; Is the column empty?
je .unit ; Then see whether to add an unit of water
dec byte [si] ; Otherwise, remove block from tower
inc bx ; And count it
jmp .next
.unit: test bl,bl ; Any blocks?
jz .next
inc ax ; If so, add unit of water
.next: inc si ; Scan rightward
cmp si,di ; Reached the right edge?
jbe .scanl ; If not, keep going
shr bl,1 ; If more than 1 block,
jnz .scanr ; Keep going
.out: ret
;;; Calculate and print the amount of water for each input
demo: mov si,series
.loop: lodsw ; Load pointer
test ax,ax ; If 0,
jz .done ; we're done.
xchg ax,dx
lodsw ; Load length
xchg ax,cx
push si ; Keep array pointer
call water ; Calculate amount of water
call prax ; Print AX
pop si ; Restore array pointer
jmp .loop
.done: ret
;;; Print AX as number
prax: mov bx,num ; Pointer to end of number string
mov cx,10 ; Divisor
.dgt: xor dx,dx ; Divide by 10
div cx
add dl,'0' ; Add ASCII 0 to remainder
dec bx ; Store digit
mov [bx],dl
test ax,ax ; If number not zero yet
jnz .dgt ; Find rest of digits
mov dx,bx ; Print number string
mov ah,9
int 21h
ret
section .data
db '*****' ; Output number placeholder
num: db ' $'
;;; Series
t1: db 1,5,3,7,2
t2: db 5,3,7,2,6,4,5,9,1,2
t3: db 2,6,3,5,2,8,1,4,2,2,5,3,5,7,4,1
t4: db 5,5,5,5
t5: db 5,6,7,8
t6: db 8,7,7,6
t7: db 6,7,10,7,6
t_end: equ $
;;; Lengths and pointers
series: dw t1,t2-t1
dw t2,t3-t2
dw t3,t4-t3
dw t4,t5-t4
dw t5,t6-t5
dw t6,t7-t6
dw t7,t_end-t7
dw 0</syntaxhighlight>
{{out}}
<pre>2 14 35 0 0 0 0</pre>
=={{header|Action!}}==
<syntaxhighlight lang="action!">PROC PrintArray(BYTE ARRAY a BYTE len)
BYTE i
Put('[)
FOR i=0 TO len-1
DO
IF i>0 THEN
Put(32)
FI
PrintB(a(i))
OD
Put('])
RETURN
BYTE FUNC Max(BYTE ARRAY a BYTE start,stop)
BYTE i,res
res=0
FOR i=start TO stop
DO
IF a(i)>res THEN
res=a(i)
FI
OD
RETURN (res)
BYTE FUNC CalcWater(BYTE ARRAY a BYTE len)
BYTE water,i,maxL,maxR,lev
IF len<3 THEN
RETURN (0)
FI
water=0
FOR i=1 TO len-2
DO
maxL=Max(a,0,i-1)
maxR=Max(a,i+1,len-1)
IF maxL<maxR THEN
lev=maxL
ELSE
lev=maxR
FI
IF a(i)<lev THEN
water==+lev-a(i)
FI
OD
RETURN (water)
PROC Test(BYTE ARRAY a BYTE len)
BYTE water
water=CalcWater(a,len)
PrintArray(a,len)
PrintF(" holds %B water units%E%E",water)
RETURN
PROC Main()
DEFINE COUNT="7"
BYTE ARRAY
a1=[1 5 3 7 2],
a2=[5 3 7 2 6 4 5 9 1 2],
a3=[2 6 3 5 2 8 1 4 2 2 5 3 5 7 4 1],
a4=[5 5 5 5],
a5=[5 6 7 8],
a6=[8 7 7 6],
a7=[6 7 10 7 6]
Test(a1,5)
Test(a2,10)
Test(a3,16)
Test(a4,4)
Test(a5,4)
Test(a6,4)
Test(a7,5)
RETURN</syntaxhighlight>
{{out}}
[https://gitlab.com/amarok8bit/action-rosetta-code/-/raw/master/images/Water_collected_between_towers.png Screenshot from Atari 8-bit computer]
<pre>
[1 5 3 7 2] holds 2 water units
[5 3 7 2 6 4 5 9 1 2] holds 14 water units
[2 6 3 5 2 8 1 4 2 2 5 3 5 7 4 1] holds 35 water units
[5 5 5 5] holds 0 water units
[5 6 7 8] holds 0 water units
[8 7 7 6] holds 0 water units
[6 7 10 7 6] holds 0 water units
</pre>
=={{header|Ada}}==
<syntaxhighlight lang="ada">with Ada.Text_IO;
procedure Water_Collected is
type Bar_Index is new Positive;
type Natural_Array is array (Bar_Index range <>) of Natural;
subtype Bar_Array is Natural_Array;
subtype Water_Array is Natural_Array;
function Flood (Bars : Bar_Array; Forward : Boolean) return Water_Array is
R : Water_Array (Bars'Range);
H : Natural := 0;
begin
if Forward then
for A in R'Range loop
H := Natural'Max (H, Bars (A));
R (A) := H - Bars (A);
end loop;
else
for A in reverse R'Range loop
H := Natural'Max (H, Bars (A));
R (A) := H - Bars (A);
end loop;
end if;
return R;
end Flood;
function Fold (Left, Right : Water_Array) return Water_Array is
R : Water_Array (Left'Range);
begin
for A in R'Range loop
R (A) := Natural'Min (Left (A), Right (A));
end loop;
return R;
end Fold;
function Fill (Bars : Bar_Array) return Water_Array
is (Fold (Flood (Bars, Forward => True),
Flood (Bars, Forward => False)));
function Sum_Of (Bars : Natural_Array) return Natural is
Sum : Natural := 0;
begin
for Bar of Bars loop
Sum := Sum + Bar;
end loop;
return Sum;
end Sum_Of;
procedure Show (Bars : Bar_Array) is
use Ada.Text_IO;
Water : constant Water_Array := Fill (Bars);
begin
Put ("The series: [");
for Bar of Bars loop
Put (Bar'Image);
Put (" ");
end loop;
Put ("] holds ");
Put (Sum_Of (Water)'Image);
Put (" units of water.");
New_Line;
end Show;
begin
Show ((1, 5, 3, 7, 2));
Show ((5, 3, 7, 2, 6, 4, 5, 9, 1, 2));
Show ((2, 6, 3, 5, 2, 8, 1, 4, 2, 2, 5, 3, 5, 7, 4, 1));
Show ((5, 5, 5, 5));
Show ((5, 6, 7, 8));
Show ((8, 7, 7, 6));
Show ((6, 7, 10, 7, 6));
end Water_Collected;</syntaxhighlight>
{{out}}
<pre>
The series: [ 1 5 3 7 2 ] holds 2 units of water.
The series: [ 5 3 7 2 6 4 5 9 1 2 ] holds 14 units of water.
The series: [ 2 6 3 5 2 8 1 4 2 2 5 3 5 7 4 1 ] holds 35 units of water.
The series: [ 5 5 5 5 ] holds 0 units of water.
The series: [ 5 6 7 8 ] holds 0 units of water.
The series: [ 8 7 7 6 ] holds 0 units of water.
The series: [ 6 7 10 7 6 ] holds 0 units of water.
</pre>
=={{header|AppleScript}}==
{{Trans|JavaScript}}
<syntaxhighlight lang="applescript">--------------- WATER COLLECTED BETWEEN TOWERS -------------
-- waterCollected :: [Int] -> Int
on waterCollected(xs)
set leftWalls to scanl1(my max, xs)
Line 53 ⟶ 488:
-- positive :: Num a => a -> Bool
script positive
on
x > 0
end
end script
-- minus :: Num a => a -> a -> a
script minus
on
a - b
end
end script
Line 69 ⟶ 504:
---------------------------- TEST --------------------------
on run
map(waterCollected, ¬
Line 85 ⟶ 519:
--------------------- GENERIC FUNCTIONS --------------------
-- filter :: (a -> Bool) -> [a] -> [a]
on filter(f, xs)
tell mReturn(f)
set lst to {}
set lng to length of xs
repeat with i from 1 to lng
set v to item i of xs
if |λ|(v, i, xs) then set end of lst to v
end repeat
return lst
end tell
end filter
--
on
tell mReturn(f)
set lng to length of xs
repeat with i from 1 to lng
set v to |λ|(v, item i of xs, i, xs)
end repeat
return v
end tell
end foldl
-- init :: [a] -> [a]
on init(xs)
if length of xs > 1 then
items 1 thru -2 of xs
else
{}
end if
end
--
on
tell mReturn(f)
set lst to {}
repeat with i from 1 to lng
set end of lst to |λ|(item i of xs, i, xs)
end repeat
return lst
end tell
end map
-- max :: Ord a => a -> a -> a
on max(x, y)
if x > y then
x
else
end if
end
-- min :: Ord a => a -> a -> a
on min(x, y)
if y < x then
y
else
x
end if
end min
-- Lift 2nd class handler function into 1st class script wrapper
-- mReturn :: Handler -> Script
on mReturn(f)
if class of f is script then
f
else
script
property |λ| : f
end script
end if
end mReturn
-- scanl :: (b -> a -> b) -> b -> [a] -> [b]
Line 113 ⟶ 604:
set lst to {startValue}
repeat with i from 1 to lng
set v to
set end of lst to v
end repeat
Line 119 ⟶ 610:
end tell
end scanl
-- scanl1 :: (a -> a -> a) -> [a] -> [a]
on scanl1(f, xs)
if length of xs > 0 then
scanl(f, item 1 of xs, items 2 thru -1 of xs)
else
{}
end if
end scanl1
-- scanr :: (b -> a -> b) -> b -> [a] -> [b]
Line 127 ⟶ 627:
set lst to {startValue}
repeat with i from lng to 1 by -1
set v to
set end of lst to v
end repeat
Line 134 ⟶ 634:
end scanr
--
on
scanr(f, item -1 of xs, items 1 thru -2 of xs)
else
{}
end if
end
-- sum :: Num a => [a] -> a
on sum(xs)
script add
on
a + b
end
end script
foldl(add, 0, xs)
end sum
-- tail :: [a] -> [a]
Line 230 ⟶ 663:
end tail
--
on
set lng to min(length of xs, length of ys)
set lst to
set end of lst to |λ|(item i of xs, item i of ys)
end
return lst
end tell
end zipWith</syntaxhighlight>
{{Out}}
<syntaxhighlight lang="applescript">{2, 14, 35, 0, 0, 0, 0}</syntaxhighlight>
=={{header|Arturo}}==
<syntaxhighlight lang="arturo">cmax: function => [
m: neg ∞
map & 'x -> m:<=max @[m x]
]
vmin: $ => [map couple & & =>
vsub: $ => [map couple & & 'p -> p\0 - p\1]
water: function [a][
sum vsub vmin reverse cmax reverse a cmax a a
]
loop [
[1, 5, 3, 7, 2],
[5, 3, 7, 2, 6, 4, 5, 9, 1, 2],
[2, 6, 3, 5, 2, 8, 1, 4, 2, 2, 5, 3, 5, 7, 4, 1],
[5, 5, 5, 5],
[5, 6, 7, 8],
[8, 7, 7, 6],
[6, 7, 10, 7, 6]
] 'a -> print [a "->" water a]</syntaxhighlight>
{{out}}
<pre>[1 5 3 7 2] -> 2
[5 3 7 2 6 4 5 9 1 2] -> 14
[2 6 3 5 2 8 1 4 2 2 5 3 5 7 4 1] -> 35
[5 5 5 5] -> 0
[5 6 7 8] -> 0
[8 7 7 6] -> 0
[6 7 10 7 6] -> 0</pre>
=={{header|AutoHotkey}}==
<syntaxhighlight lang="autohotkey">WCBT(oTwr){
topL := Max(oTwr*), l := num := 0, barCh := lbarCh := "", oLvl := []
while (++l <= topL)
for t, h in oTwr
oLvl[l,t] := h ? "██" : "≈≈" , oTwr[t] := oTwr[t]>0 ? oTwr[t]-1 : 0
for l, obj in oLvl{
while (oLvl[l, A_Index] = "≈≈")
oLvl[l, A_Index] := " "
while (oLvl[l, obj.Count() +1 - A_Index] = "≈≈")
oLvl[l, obj.Count() +1 - A_Index] := " "
for t, v in obj
lbarCh .= StrReplace(v, "≈≈", "≈≈", n), num += n
barCh := lbarCh "`n" barCh, lbarCh := ""
}
return [num, barCh]
}</syntaxhighlight>
Examples:<syntaxhighlight lang="autohotkey">data := [[1, 5, 3, 7, 2]
,[5, 3, 7, 2, 6, 4, 5, 9, 1, 2]
,[2, 6, 3, 5, 2, 8, 1, 4, 2, 2, 5, 3, 5, 7, 4, 1]
,[5, 5, 5, 5]
,[5, 6, 7, 8]
,[8, 7, 7, 6]
,[6, 7, 10, 7, 6]]
result := ""
for i, oTwr in data{
inp := ""
for i, h in oTwr
inp .= h ", "
inp := "[" Trim(inp, ", ") "]"
x := WCBT(oTwr)
result .= "Chart " inp " has " x.1 " water units`n" x.2 "------------------------`n"
}
MsgBox % result</syntaxhighlight>
{{out}}
<pre>Chart [1, 5, 3, 7, 2] has 2 water units
██
██
██≈≈██
██≈≈██
██████
████████
██████████
------------------------
Chart [5, 3, 7, 2, 6, 4, 5, 9, 1, 2] has 14 water units
██
██
██≈≈≈≈≈≈≈≈██
██≈≈██≈≈≈≈██
██≈≈██≈≈██≈≈████
██≈≈██≈≈████████
██████≈≈████████
████████████████≈≈██
████████████████████
------------------------
Chart [2, 6, 3, 5, 2, 8, 1, 4, 2, 2, 5, 3, 5, 7, 4, 1] has 35 water units
██
██≈≈≈≈≈≈≈≈≈≈≈≈≈≈██
██≈≈≈≈≈≈██≈≈≈≈≈≈≈≈≈≈≈≈≈≈██
██≈≈██≈≈██≈≈≈≈≈≈≈≈██≈≈████
██≈≈██≈≈██≈≈██≈≈≈≈██≈≈██████
██████≈≈██≈≈██≈≈≈≈██████████
████████████≈≈████████████████
████████████████████████████████
------------------------
Chart [5, 5, 5, 5] has 0 water units
████████
████████
████████
████████
████████
------------------------
Chart [5, 6, 7, 8] has 0 water units
██
████
██████
████████
████████
████████
████████
████████
------------------------
Chart [8, 7, 7, 6] has 0 water units
██
██████
████████
████████
████████
████████
████████
████████
------------------------
Chart [6, 7, 10, 7, 6] has 0 water units
██
██
██
██████
██████████
██████████
██████████
██████████
██████████
██████████
------------------------</pre>
=={{header|AWK}}==
<syntaxhighlight lang="awk">
# syntax: GAWK -f WATER_COLLECTED_BETWEEN_TOWERS.AWK [-v debug={0|1}]
BEGIN {
Line 292 ⟶ 851:
function max(x,y) { return((x > y) ? x : y) }
function min(x,y) { return((x < y) ? x : y) }
</syntaxhighlight>
{{out}}
<pre>
Line 302 ⟶ 861:
0 : 8,7,7,6
0 : 6,7,10,7,6
</pre>
=={{header|BASIC}}==
==={{header|FreeBASIC}}===
Uses Nigel Galloway's very elegant idea, expressed verbosely so you can really see what's going on.
<syntaxhighlight lang="freebasic">type tower
hght as uinteger
posi as uinteger
end type
sub shellsort( a() as tower )
'quick and dirty shellsort, not the focus of this exercise
dim as uinteger gap = ubound(a), i, j, n=ubound(a)
dim as tower temp
do
gap = int(gap / 2.2)
if gap=0 then gap=1
for i=gap to n
temp = a(i)
j=i
while j>=gap andalso a(j-gap).hght < temp.hght
a(j) = a(j - gap)
j -= gap
wend
a(j) = temp
next i
loop until gap = 1
end sub
'heights of towers in each city prefixed by the number of towers
data 5, 1, 5, 3, 7, 2
data 10, 5, 3, 7, 2, 6, 4, 5, 9, 1, 2
data 16, 2, 6, 3, 5, 2, 8, 1, 4, 2, 2, 5, 3, 5, 7, 4, 1
data 4, 5, 5, 5, 5
data 4, 5, 6, 7, 8
data 4, 8, 7, 7, 6
data 5, 6, 7, 10, 7, 6
dim as uinteger i, n, j, first, last, water
dim as tower manhattan(0 to 1)
for i = 1 to 7
read n
redim manhattan( 0 to n-1 )
for j = 0 to n-1
read manhattan(j).hght
manhattan(j).posi = j
next j
shellsort( manhattan() )
if manhattan(0).posi < manhattan(1).posi then
first = manhattan(0).posi
last = manhattan(1).posi
else
first = manhattan(1).posi
last = manhattan(0).posi
end if
water = manhattan(1).hght * (last-first-1)
for j = 2 to n-1
if first<manhattan(j).posi and manhattan(j).posi<last then water -= manhattan(j).hght
if manhattan(j).posi < first then
water += manhattan(j).hght * (first-manhattan(j).posi-1)
first = manhattan(j).posi
end if
if manhattan(j).posi > last then
water += manhattan(j).hght * (manhattan(j).posi-last-1)
last = manhattan(j).posi
end if
next j
print using "City configuration ## collected #### units of water."; i; water
next i</syntaxhighlight>
{{out}}
<pre>City configuration 1 collected 2 units of water.
City configuration 2 collected 14 units of water.
City configuration 3 collected 35 units of water.
City configuration 4 collected 0 units of water.
City configuration 5 collected 0 units of water.
City configuration 6 collected 0 units of water.
City configuration 7 collected 0 units of water.</pre>
==={{header|GW-BASIC}}===
{{works with|BASICA}}
<syntaxhighlight lang="gwbasic">10 DEFINT A-Z: DIM T(20): K=0
20 K=K+1: READ N: IF N=0 THEN END
30 FOR I=0 TO N-1: READ T(I): NEXT
40 W=0
50 FOR R=N-1 TO 0 STEP -1: IF T(R)=0 THEN NEXT ELSE IF R=0 THEN 110
60 B=0
70 FOR C=0 TO R
80 IF T(C)>0 THEN T(C)=T(C)-1: B=B+1 ELSE IF B>0 THEN W=W+1
90 NEXT
100 IF B>1 THEN 50
110 PRINT "Block";K;"holds";W;"water units."
120 GOTO 20
130 DATA 5, 1,5,3,7,2
140 DATA 10, 5,3,7,2,6,4,5,9,1,2
150 DATA 16, 2,6,3,5,2,8,1,4,2,2,5,3,5,7,4,1
160 DATA 4, 5,5,5,5
170 DATA 4, 5,6,7,8
180 DATA 4, 8,7,7,6
190 DATA 5, 6,7,10,7,6
200 DATA 0</syntaxhighlight>
{{out}}
<pre>Block 1 holds 2 water units.
Block 2 holds 14 water units.
Block 3 holds 35 water units.
Block 4 holds 0 water units.
Block 5 holds 0 water units.
Block 6 holds 0 water units.
Block 7 holds 0 water units.</pre>
==={{header|Nascom BASIC}}===
{{trans|FreeBasic}}
{{works with|Nascom ROM BASIC|4.7}}
<syntaxhighlight lang="basic">
10 REM Water collected between towers
20 MXN=19
30 REM Heights of towers in each city
40 REM prefixed by the number of towers
50 DATA 5,1,5,3,7,2
60 DATA 10,5,3,7,2,6,4,5,9,1,2
70 DATA 16,2,6,3,5,2,8,1,4,2,2,5,3,5,7,4,1
80 DATA 4,5,5,5,5
90 DATA 4,5,6,7,8
100 DATA 4,8,7,7,6
110 DATA 5,6,7,10,7,6
120 DIM A(MXN,1)
130 FOR I=1 TO 7
140 READ N
150 FOR J=0 TO N-1
160 READ A(J,0)
170 A(J,1)=J
180 NEXT J
190 GOSUB 390
200 IF A(0,1)>=A(1,1) THEN 220
210 FRST=A(0,1):LST=A(1,1):GOTO 230
220 FRST=A(1,1):LST=A(0,1)
230 WTR=A(1,0)*(LST-FRST-1)
240 FOR J=2 TO N-1
250 IF FRST>=A(J,1) OR A(J,1)>=LST THEN 270
260 WTR=WTR-A(J,0)
270 IF A(J,1)>=FRST THEN 300
280 WTR=WTR+A(J,0)*(FRST-A(J,1)-1)
290 FRST=A(J,1)
300 IF A(J,1)<=LST THEN 330
310 WTR=WTR+A(J,0)*(A(J,1)-LST-1)
320 LST=A(J,1)
330 NEXT J
340 PRINT "Bar chart";I;"collected";
350 PRINT WTR;"units of water."
360 NEXT I
370 END
380 REM ** ShellSort
390 GAP=N-1
400 GAP=INT(GAP/2.2)
410 IF GAP=0 THEN GAP=1
420 FOR K=GAP TO N-1
430 TH=A(K,0):TP=A(K,1)
440 L=K
450 IF L<GAP THEN 500
460 IF A(L-GAP,0)>=TH THEN 500
470 A(L,0)=A(L-GAP,0):A(L,1)=A(L-GAP,1)
480 L=L-GAP
490 GOTO 450
500 A(L,0)=TH:A(L,1)=TP
510 NEXT K
520 IF GAP<>1 THEN 400
530 RETURN
</syntaxhighlight>
{{out}}
<pre>
Bar chart 1 collected 2 units of water.
Bar chart 2 collected 14 units of water.
Bar chart 3 collected 35 units of water.
Bar chart 4 collected 0 units of water.
Bar chart 5 collected 0 units of water.
Bar chart 6 collected 0 units of water.
Bar chart 7 collected 0 units of water.
</pre>
==={{header|QuickBASIC}}===
{{trans|FreeBasic}}
<syntaxhighlight lang="qbasic">
' Water collected between towers
DECLARE SUB ShellSort (A() AS ANY)
TYPE TTowerRec
Hght AS INTEGER
Posi AS INTEGER
END TYPE
'heights of towers in each city prefixed by the number of towers
DATA 5, 1, 5, 3, 7, 2
DATA 10, 5, 3, 7, 2, 6, 4, 5, 9, 1, 2
DATA 16, 2, 6, 3, 5, 2, 8, 1, 4, 2, 2, 5, 3, 5, 7, 4, 1
DATA 4, 5, 5, 5, 5
DATA 4, 5, 6, 7, 8
DATA 4, 8, 7, 7, 6
DATA 5, 6, 7, 10, 7, 6
REM $DYNAMIC
DIM Manhattan(0 TO 1) AS TTowerRec
FOR I% = 1 TO 7
READ N%
ERASE Manhattan
REDIM Manhattan(0 TO N% - 1) AS TTowerRec
FOR J% = 0 TO N% - 1
READ Manhattan(J%).Hght
Manhattan(J%).Posi = J%
NEXT J%
ShellSort Manhattan()
IF Manhattan(0).Posi < Manhattan(1).Posi THEN
First% = Manhattan(0).Posi
Last% = Manhattan(1).Posi
ELSE
First% = Manhattan(1).Posi
Last% = Manhattan(0).Posi
END IF
Water% = Manhattan(1).Hght * (Last% - First% - 1)
FOR J% = 2 TO N% - 1
IF First% < Manhattan(J%).Posi AND Manhattan(J%).Posi < Last% THEN Water% = Water% - Manhattan(J%).Hght
IF Manhattan(J%).Posi < First% THEN
Water% = Water% + Manhattan(J%).Hght * (First% - Manhattan(J%).Posi - 1)
First% = Manhattan(J%).Posi
END IF
IF Manhattan(J%).Posi > Last% THEN
Water% = Water% + Manhattan(J%).Hght * (Manhattan(J%).Posi - Last% - 1)
Last% = Manhattan(J%).Posi
END IF
NEXT J%
PRINT USING "City configuration ## collected #### units of water."; I%; Water%
NEXT I%
END
REM $STATIC
SUB ShellSort (A() AS TTowerRec)
'quick and dirty shellsort, not the focus of this exercise
Gap% = UBOUND(A): N% = UBOUND(A)
DIM Temp AS TTowerRec
DO
Gap% = INT(Gap% / 2.2)
IF Gap% = 0 THEN Gap% = 1
FOR I% = Gap% TO N%
Temp = A(I%)
J% = I%
' Simulated WHILE J% >= Gap% ANDALSO A(J% - Gap%).Hght < Temp.Hght
DO
IF J% < Gap% THEN EXIT DO
IF A(J% - Gap%).Hght >= Temp.Hght THEN EXIT DO
A(J%) = A(J% - Gap%)
J% = J% - Gap%
LOOP
A(J%) = Temp
NEXT I%
LOOP UNTIL Gap% = 1
END SUB
</syntaxhighlight>
{{out}}
<pre>
City configuration 1 collected 2 units of water.
City configuration 2 collected 14 units of water.
City configuration 3 collected 35 units of water.
City configuration 4 collected 0 units of water.
City configuration 5 collected 0 units of water.
City configuration 6 collected 0 units of water.
City configuration 7 collected 0 units of water.
</pre>
==={{header|uBasic/4tH}}===
{{Trans|GW-BASIC}}
<syntaxhighlight lang="basic">Dim @t(20)
k = FUNC (_getWater (1, 5, 3, 7, 2, 1))
k = FUNC (_getWater (5, 3, 7, 2, 6, 4, 5, 9, 1, 2, k))
k = FUNC (_getWater (2, 6, 3, 5, 2, 8, 1, 4, 2, 2, 5, 3, 5, 7, 4, 1, k))
k = FUNC (_getWater (5, 5, 5, 5, k))
k = FUNC (_getWater (5, 6, 7, 8, k))
k = FUNC (_getWater (8, 7, 7, 6, k))
k = FUNC (_getWater (6, 7, 10, 7, 6, k))
End
_getWater
Param (1)
Local (2)
w = 0
c@ = Used()
For b@ = c@ - 1 To 0 Step -1
@t(b@) = Pop()
Next
Do While FUNC(_netWater (c@)) > 1 : Loop
Print "Block ";a@;" holds ";w;" water units."
Return (a@ + 1)
_netWater
Param (1)
Local (3)
For d@ = a@-1 To 0 Step -1
If @t(d@) Then
If d@ = 0 Then Unloop : Return (0) : fi
Else
Continue
EndIf
b@ = 0
For c@ = 0 To d@
If @t(c@) > 0 Then
@t(c@) = @t(c@) - 1
b@ = b@ + 1
Else
If b@ > 0 Then w = w + 1 : fi
EndIf
Next
Unloop : Return (b@)
Next
Return (0)</syntaxhighlight>
{{Out}}
<pre>Block 1 holds 2 water units.
Block 2 holds 14 water units.
Block 3 holds 35 water units.
Block 4 holds 0 water units.
Block 5 holds 0 water units.
Block 6 holds 0 water units.
Block 7 holds 0 water units.
0 OK, 0:409</pre>
==={{header|Visual Basic .NET}}===
====Version 1====
'''Method:''' Instead of "scanning" adjoining towers for each column, this routine converts the tower data into a string representation with building blocks, empty spaces, and potential water retention sites. The potential water retention sites are then "eroded" away where they are found to be unsupported. This is accomplished with the '''.Replace()''' function. The replace operations are unleashed upon the entire "block" of towers, rather than a cell at a time or a line at a time - which perhaps increases the program's execution-time, but reduces program's complexity.
The program can optionally display the interim string representation of each tower block before the final count is completed. I've since modified it to have the same block and wavy characters are the
[[{{FULLPAGENAME}}#version_3|REXX 9.3]] output, but used the double-wide columns, as pictured in the task definition area.
<syntaxhighlight lang="vbnet">' Convert tower block data into a string representation, then manipulate that.
Module Module1
Sub Main(Args() As String)
Dim shoTow As Boolean = Environment.GetCommandLineArgs().Count > 1 ' Show towers.
Dim wta As Integer()() = { ' Water tower array (input data).
New Integer() {1, 5, 3, 7, 2}, New Integer() {5, 3, 7, 2, 6, 4, 5, 9, 1, 2},
New Integer() {2, 6, 3, 5, 2, 8, 1, 4, 2, 2, 5, 3, 5, 7, 4, 1},
New Integer() {5, 5, 5, 5}, New Integer() {5, 6, 7, 8},
New Integer() {8, 7, 7, 6}, New Integer() {6, 7, 10, 7, 6}}
Dim blk As String, ' String representation of a block of towers.
lf As String = vbLf, ' Line feed to separate floors in a block of towers.
tb = "██", wr = "≈≈", mt = " " ' Tower Block, Water Retained, eMpTy space.
For i As Integer = 0 To wta.Length - 1
Dim bpf As Integer ' Count of tower blocks found per floor.
blk = ""
Do
bpf = 0 : Dim floor As String = "" ' String representation of each floor.
For j As Integer = 0 To wta(i).Length - 1
If wta(i)(j) > 0 Then ' Tower block detected, add block to floor,
floor &= tb : wta(i)(j) -= 1 : bpf += 1 ' reduce tower by one.
Else ' Empty space detected, fill when not first or last column.
floor &= If(j > 0 AndAlso j < wta(i).Length - 1, wr, mt)
End If
Next
If bpf > 0 Then blk = floor & lf & blk ' Add floors until blocks are gone.
Loop Until bpf = 0 ' No tower blocks left, so terminate.
' Erode potential water retention cells from left and right.
While blk.Contains(mt & wr) : blk = blk.Replace(mt & wr, mt & mt) : End While
While blk.Contains(wr & mt) : blk = blk.Replace(wr & mt, mt & mt) : End While
' Optionaly show towers w/ water marks.
If shoTow Then Console.Write("{0}{1}", lf, blk)
' Subtract the amount of non-water mark characters from the total char amount.
Console.Write("Block {0} retains {1,2} water units.{2}", i + 1,
(blk.Length - blk.Replace(wr, "").Length) \ 2, lf)
Next
End Sub
End Module</syntaxhighlight>
{{out}}<syntaxhighlight lang="text">Block 1 retains 2 water units.
Block 2 retains 14 water units.
Block 3 retains 35 water units.
Block 4 retains 0 water units.
Block 5 retains 0 water units.
Block 6 retains 0 water units.
Block 7 retains 0 water units.</syntaxhighlight>
Verbose output shows towers with water ("Almost equal to" characters) left in the "wells" between towers. Just supply any command-line parameter to see it. Use no command line parameters to see the plain output above.
<syntaxhighlight lang="text"> ██
██
██≈≈██
██≈≈██
██████
████████
██████████
Block 1 retains 2 water units.
██
██
██≈≈≈≈≈≈≈≈██
██≈≈██≈≈≈≈██
██≈≈██≈≈██≈≈████
██≈≈██≈≈████████
██████≈≈████████
████████████████≈≈██
████████████████████
Block 2 retains 14 water units.
██
██≈≈≈≈≈≈≈≈≈≈≈≈≈≈██
██≈≈≈≈≈≈██≈≈≈≈≈≈≈≈≈≈≈≈≈≈██
██≈≈██≈≈██≈≈≈≈≈≈≈≈██≈≈████
██≈≈██≈≈██≈≈██≈≈≈≈██≈≈██████
██████≈≈██≈≈██≈≈≈≈██████████
████████████≈≈████████████████
████████████████████████████████
Block 3 retains 35 water units.
████████
████████
████████
████████
████████
Block 4 retains 0 water units.
██
████
██████
████████
████████
████████
████████
████████
Block 5 retains 0 water units.
██
██████
████████
████████
████████
████████
████████
████████
Block 6 retains 0 water units.
██
██
██
██████
██████████
██████████
██████████
██████████
██████████
██████████
Block 7 retains 0 water units.</syntaxhighlight>
====Version 2====
'''Method:''' More conventional "scanning" method. A Char array is used, but no Replace() statements. Output is similar to version 1, although there is now a left margin of three spaces, the results statement is immediately to the right of the string representation of the tower blocks (instead of underneath), the verb is "hold(s)" instead of "retains", and there is a special string when the results indicate zero.
<syntaxhighlight lang="vbnet">Module Module1
''' <summary>
''' wide - Widens the aspect ratio of a linefeed separated string.
''' </summary>
''' <param name="src">A string representing a block of towers.</param>
''' <param name="margin">Optional padding for area to the left.</param>
''' <returns>A double-wide version of the string.</returns>
Function wide(src As String, Optional margin As String = "") As String
Dim res As String = margin : For Each ch As Char In src
res += If(ch < " ", ch & margin, ch + ch) : Next : Return res
End Function
''' <summary>
''' cntChar - Counts characters, also custom formats the output.
''' </summary>
''' <param name="src">The string to count characters in.</param>
''' <param name="ch">The character to be counted.</param>
''' <param name="verb">Verb to include in format. Expecting "hold",
''' but can work with "retain" or "have".</param>
''' <returns>The count of chars found in a string, and formats a verb.</returns>
Function cntChar(src As String, ch As Char, verb As String) As String
Dim cnt As Integer = 0
For Each c As Char In src : cnt += If(c = ch, 1, 0) : Next
Return If(cnt = 0, "does not " & verb & " any",
verb.Substring(0, If(verb = "have", 2, 4)) & "s " & cnt.ToString())
End Function
''' <summary>
''' report - Produces a report of the number of rain units found in
''' a block of towers, optionally showing the towers.
''' Autoincrements the blkID for each report.
''' </summary>
''' <param name="tea">An int array with tower elevations.</param>
''' <param name="blkID">An int of the block of towers ID.</param>
''' <param name="verb">The verb to use in the description.
''' Defaults to "has / have".</param>
''' <param name="showIt">When true, the report includes a string representation
''' of the block of towers.</param>
''' <returns>A string containing the amount of rain units, optionally preceeded by
''' a string representation of the towers holding any water.</returns>
Function report(tea As Integer(), ' Tower elevation array.
ByRef blkID As Integer, ' Block ID for the description.
Optional verb As String = "have", ' Verb to use in the description.
Optional showIt As Boolean = False) As String ' Show representaion.
Dim block As String = "", ' The block of towers.
lf As String = vbLf, ' The separator between floors.
rTwrPos As Integer ' The position of the rightmost tower of this floor.
Do
For rTwrPos = tea.Length - 1 To 0 Step -1 ' Determine the rightmost tower
If tea(rTwrPos) > 0 Then Exit For ' postition on this floor.
Next
If rTwrPos < 0 Then Exit Do ' When no towers remain, exit the do loop.
' init the floor to a space filled Char array, as wide as the block of towers.
Dim floor As Char() = New String(" ", tea.Length).ToCharArray()
Dim bpf As Integer = 0 ' The count of blocks found per floor.
For column As Integer = 0 To rTwrPos ' Scan from left to right.
If tea(column) > 0 Then ' If a tower exists here,
floor(column) = "█" ' mark the floor with a block,
tea(column) -= 1 ' drop the tower elevation by one,
bpf += 1 ' and advance the block count.
ElseIf bpf > 0 Then ' Otherwise, see if a tower is present to the left.
floor(column) = "≈" ' OK to fill with water.
End If
Next
If bpf > If(showIt, 0, 1) Then ' Continue the building only when needed.
' If not showing blocks, discontinue building when a single tower remains.
' build tower blocks string with each floor added to top.
block = New String(floor) & If(block = "", "", lf) & block
Else
Exit Do ' Ran out of towers, so exit the do loop.
End If
Loop While True ' Depending on previous break statements to terminate the do loop.
blkID += 1 ' increment block ID counter.
' format report and return it.
Return If(showIt, String.Format(vbLf & "{0}", wide(block, " ")), "") &
String.Format(" Block {0} {1} water units.", blkID, cntChar(block, "≈", verb))
End Function
''' <summary>
''' Main routine.
'''
''' With one command line parameter, it shows tower blocks,
''' with no command line parameters, it shows a plain report
'''</summary>
Sub Main()
Dim shoTow As Boolean = Environment.GetCommandLineArgs().Count > 1 ' Show towers.
Dim blkCntr As Integer = 0 ' Block ID for reports.
Dim verb As String = "hold" ' "retain" or "have" can be used instead of "hold".
Dim tea As Integer()() = {New Integer() {1, 5, 3, 7, 2}, ' Tower elevation data.
New Integer() {5, 3, 7, 2, 6, 4, 5, 9, 1, 2},
New Integer() {2, 6, 3, 5, 2, 8, 1, 4, 2, 2, 5, 3, 5, 7, 4, 1},
New Integer() {5, 5, 5, 5}, New Integer() {5, 6, 7, 8},
New Integer() {8, 7, 7, 6}, New Integer() {6, 7, 10, 7, 6}}
For Each block As Integer() In tea
' Produce report for each block of towers.
Console.WriteLine(report(block, blkCntr, verb, shoTow))
Next
End Sub
End Module</syntaxhighlight>
Regular version 2 output:
<syntaxhighlight lang="text"> Block 1 holds 2 water units.
Block 2 holds 14 water units.
Block 3 holds 35 water units.
Block 4 does not hold any water units.
Block 5 does not hold any water units.
Block 6 does not hold any water units.
Block 7 does not hold any water units.</syntaxhighlight>
Sample of version 2 verbose output:
<syntaxhighlight lang="text"> ██
██≈≈≈≈≈≈≈≈≈≈≈≈≈≈██
██≈≈≈≈≈≈██≈≈≈≈≈≈≈≈≈≈≈≈≈≈██
██≈≈██≈≈██≈≈≈≈≈≈≈≈██≈≈████
██≈≈██≈≈██≈≈██≈≈≈≈██≈≈██████
██████≈≈██≈≈██≈≈≈≈██████████
████████████≈≈████████████████
████████████████████████████████ Block 3 holds 35 water units.
████████
████████
████████
████████
████████ Block 4 does not hold any water units.</syntaxhighlight>
==={{header|Yabasic}}===
{{trans|AWK}}
<syntaxhighlight lang="yabasic">data 7
data "1,5,3,7,2", "5,3,7,2,6,4,5,9,1,2", "2,6,3,5,2,8,1,4,2,2,5,3,5,7,4,1"
data "5,5,5,5", "5,6,7,8", "8,7,7,6", "6,7,10,7,6"
read n
for i = 1 to n
read n$
wcbt(n$)
next i
sub wcbt(s$)
local tower$(1), hr(1), hl(1), n, i, ans, k
n = token(s$, tower$(), ",")
redim hr(n)
redim hl(n)
for i = n to 1 step -1
if i < n then
k = hr(i + 1)
else
k = 0
end if
hr(i) = max(val(tower$(i)), k)
next i
for i = 1 to n
if i then
k = hl(i - 1)
else
k = 0
end if
hl(i) = max(val(tower$(i)), k)
ans = ans + min(hl(i), hr(i)) - val(tower$(i))
next i
print ans," ",n$
end sub</syntaxhighlight>
=={{header|C}}==
Takes the integers as input from command line, prints out usage on incorrect invocation.
<syntaxhighlight lang="c">
#include<stdlib.h>
#include<stdio.h>
int getWater(int* arr,int start,int end,int cutoff){
int i, sum = 0;
for(i=start;i<=end;i++)
sum += ((arr[cutoff] > arr[i])?(arr[cutoff] - arr[i]):0);
return sum;
}
int netWater(int* arr,int size){
int i, j, ref1, ref2, marker, markerSet = 0,sum = 0;
if(size<3)
return 0;
for(i=0;i<size-1;i++){
start:if(i!=size-2 && arr[i]>arr[i+1]){
ref1 = i;
for(j=ref1+1;j<size;j++){
if(arr[j]>=arr[ref1]){
ref2 = j;
sum += getWater(arr,ref1+1,ref2-1,ref1);
i = ref2;
goto start;
}
else if(j!=size-1 && arr[j] < arr[j+1] && (markerSet==0||(arr[j+1]>=arr[marker]))){
marker = j+1;
markerSet = 1;
}
}
if(markerSet==1){
sum += getWater(arr,ref1+1,marker-1,marker);
i = marker;
markerSet = 0;
goto start;
}
}
}
return sum;
}
int main(int argC,char* argV[])
{
int *arr,i;
if(argC==1)
printf("Usage : %s <followed by space separated series of integers>");
else{
arr = (int*)malloc((argC-1)*sizeof(int));
for(i=1;i<argC;i++)
arr[i-1] = atoi(argV[i]);
printf("Water collected : %d",netWater(arr,argC-1));
}
return 0;
}
</syntaxhighlight>
Output :
<pre>
C:\rosettaCode>waterTowers.exe 1 5 3 7 2
Water collected : 2
C:\rosettaCode>waterTowers.exe 5 3 7 2 6 4 5 9 1 2
Water collected : 14
C:\rosettaCode>waterTowers.exe 2 6 3 5 2 8 1 4 2 2 5 3 5 7 4 1
Water collected : 35
C:\rosettaCode>waterTowers.exe 5 5 5 5
Water collected : 0
C:\rosettaCode>waterTowers.exe 8 7 7 6
Water collected : 0
C:\rosettaCode>waterTowers.exe 6 7 10 7 6
Water collected : 0
</pre>
=={{header|C sharp|C#}}==
===Version 1===
Translation from [[{{FULLPAGENAME}}#Visual_Basic_.NET|Visual Basic .NET]]. See that version 1 entry for code comment details and more sample output.
<syntaxhighlight lang="csharp">class Program
{
static void Main(string[] args)
{
int[][] wta = {
new int[] {1, 5, 3, 7, 2}, new int[] { 5, 3, 7, 2, 6, 4, 5, 9, 1, 2 },
new int[] { 2, 6, 3, 5, 2, 8, 1, 4, 2, 2, 5, 3, 5, 7, 4, 1 },
new int[] { 5, 5, 5, 5 }, new int[] { 5, 6, 7, 8 },
new int[] { 8, 7, 7, 6 }, new int[] { 6, 7, 10, 7, 6 }};
string blk, lf = "\n", tb = "██", wr = "≈≈", mt = " ";
for (int i = 0; i < wta.Length; i++)
{
int bpf; blk = ""; do
{
string floor = ""; bpf = 0; for (int j = 0; j < wta[i].Length; j++)
{
if (wta[i][j] > 0)
{ floor += tb; wta[i][j] -= 1; bpf += 1; }
else floor += (j > 0 && j < wta[i].Length - 1 ? wr : mt);
}
if (bpf > 0) blk = floor + lf + blk;
} while (bpf > 0);
while (blk.Contains(mt + wr)) blk = blk.Replace(mt + wr, mt + mt);
while (blk.Contains(wr + mt)) blk = blk.Replace(wr + mt, mt + mt);
if (args.Length > 0) System.Console.Write("\n{0}", blk);
System.Console.WriteLine("Block {0} retains {1,2} water units.",
i + 1, (blk.Length - blk.Replace(wr, "").Length) / 2);
}
}
}</syntaxhighlight>{{out}}<syntaxhighlight lang="text">Block 1 retains 2 water units.
Block 2 retains 14 water units.
Block 3 retains 35 water units.
Block 4 retains 0 water units.
Block 5 retains 0 water units.
Block 6 retains 0 water units.
Block 7 retains 0 water units.</syntaxhighlight>
===Version 2===
Conventional "scanning" algorithm, translated from [[{{FULLPAGENAME}}#Version_2_2|the second version of Visual Basic.NET]], but (intentionally tweaked to be) incapable of verbose output. See that version 2 entry for code comments and details.
<syntaxhighlight lang="csharp">class Program
{
// Variable names key:
// i Iterator (of the tower block array).
// tba Tower block array.
// tea Tower elevation array.
// rht Right hand tower column number (position).
// wu Water units (count).
// bof Blocks on floor (count).
// col Column number in elevation array (position).
static void Main(string[] args)
{
int i = 1; int[][] tba = {new int[] { 1, 5, 3, 7, 2 },
new int[] { 5, 3, 7, 2, 6, 4, 5, 9, 1, 2 },
new int[] { 2, 6, 3, 5, 2, 8, 1, 4, 2, 2, 5, 3, 5, 7, 4, 1 },
new int[] { 5, 5, 5, 5 }, new int[] { 5, 6, 7, 8 },
new int[] { 8, 7, 7, 6 }, new int[] { 6, 7, 10, 7, 6 }};
foreach (int[] tea in tba)
{
int rht, wu = 0, bof; do
{
for (rht = tea.Length - 1; rht >= 0; rht--)
if (tea[rht] > 0) break;
if (rht < 0) break;
bof = 0; for (int col = 0; col <= rht; col++)
{
if (tea[col] > 0) { tea[col] -= 1; bof += 1; }
else if (bof > 0) wu++;
}
if (bof < 2) break;
} while (true);
System.Console.WriteLine(string.Format("Block {0} {1} water units.",
i++, wu == 0 ? "does not hold any" : "holds " + wu.ToString()));
}
}
}</syntaxhighlight>
'''Output:'''
<pre>Block 1 holds 2 water units.
Block 2 holds 14 water units.
Block 3 holds 35 water units.
Block 4 does not hold any water units.
Block 5 does not hold any water units.
Block 6 does not hold any water units.
Block 7 does not hold any water units.</pre>
=={{header|C++}}==
<syntaxhighlight lang="cpp">
#include <iostream>
#include <vector>
#include <algorithm>
enum { EMPTY, WALL, WATER };
auto fill(const std::vector<int> b) {
auto water = 0;
const auto rows = *std::max_element(std::begin(b), std::end(b));
const auto cols = std::size(b);
std::vector<std::vector<int>> g(rows);
for (auto& r : g) {
for (auto i = 0; i < cols; ++i) {
r.push_back(EMPTY);
}
}
for (auto c = 0; c < cols; ++c) {
for (auto r = rows - 1u, i = 0u; i < b[c]; ++i, --r) {
g[r][c] = WALL;
}
}
for (auto c = 0; c < cols - 1; ++c) {
auto start_row = rows - b[c];
while (start_row < rows) {
if (g[start_row][c] == EMPTY) break;
auto c2 = c + 1;
bool hitWall = false;
while (c2 < cols) {
if (g[start_row][c2] == WALL) {
hitWall = true;
break;
}
++c2;
}
if (hitWall) {
for (auto i = c + 1; i < c2; ++i) {
g[start_row][i] = WATER;
++water;
}
}
++start_row;
}
}
return water;
}
int main() {
std::vector<std::vector<int>> b = {
{ 1, 5, 3, 7, 2 },
{ 5, 3, 7, 2, 6, 4, 5, 9, 1, 2 },
{ 2, 6, 3, 5, 2, 8, 1, 4, 2, 2, 5, 3, 5, 7, 4, 1 },
{ 5, 5, 5, 5 },
{ 5, 6, 7, 8 },
{ 8, 7, 7, 6 },
{ 6, 7, 10, 7, 6 }
};
for (const auto v : b) {
auto water = fill(v);
std::cout << water << " water drops." << std::endl;
}
std::cin.ignore();
std::cin.get();
return 0;
}</syntaxhighlight>
{{out}}
<pre>2 water drops.
14 water drops.
35 water drops.
0 water drops.
0 water drops.
0 water drops.
0 water drops.</pre>
=={{header|Clojure}}==
Similar two passes algorithm as many solutions here. First traverse left to right to find the highest tower on the left of each position, inclusive of the tower at the current position, than do the same to find the highest tower to the right of each position. Finally, compute the total water units held at any position as the difference of those two heights.
<syntaxhighlight lang="clojure">
(defn trapped-water [towers]
(let [maxes #(reductions max %) ; the seq of increasing max values found in the input seq
maxl (maxes towers) ; the seq of max heights to the left of each tower
maxr (reverse (maxes (reverse towers))) ; the seq of max heights to the right of each tower
mins (map min maxl maxr)] ; minimum highest surrounding tower per position
(reduce + (map - mins towers)))) ; sum up the trapped water per position
</syntaxhighlight>
{{out}}
<syntaxhighlight lang="clojure">
;; in the following, # is a tower block and ~ is trapped water:
;;
;; 10|
;; 9| #
;; 8| #
;; 7| # ~ ~ ~ ~ #
;; 6| # ~ # ~ ~ #
;; 5| # ~ # ~ # ~ # #
;; 4| # ~ # ~ # # # #
;; 3| # # # ~ # # # #
;; 2| # # # # # # # # ~ #
;; 1| # # # # # # # # # #
;; ---+---------------------
;; 5 3 7 2 6 4 5 9 1 2
(trapped-water [5 3 7 2 6 4 5 9 1 2]) ;; 14
</syntaxhighlight>
=={{header|CLU}}==
<syntaxhighlight lang="clu">max = proc [T: type] (a,b: T) returns (T)
where T has lt: proctype (T,T) returns (bool)
if a<b then return(b)
else return(a)
end
end max
% based on: https://stackoverflow.com/a/42821623
water = proc (towers: sequence[int]) returns (int)
si = sequence[int]
w: int := 0
left: int := 1
right: int := si$size(towers)
max_left: int := si$bottom(towers)
max_right: int := si$top(towers)
while left <= right do
if towers[left] <= towers[right] then
max_left := max[int](towers[left], max_left)
w := w + max[int](max_left - towers[left], 0)
left := left + 1
else
max_right := max[int](towers[right], max_right)
w := w + max[int](max_right - towers[right], 0)
right := right - 1
end
end
return(w)
end water
start_up = proc ()
si = sequence[int]
ssi = sequence[si]
po: stream := stream$primary_output()
tests: ssi := ssi$[
si$[1, 5, 3, 7, 2],
si$[5, 3, 7, 2, 6, 4, 5, 9, 1, 2],
si$[2, 6, 3, 5, 2, 8, 1, 4, 2, 2, 5, 3, 5, 7, 4, 1],
si$[5, 5, 5, 5],
si$[5, 6, 7, 8],
si$[8, 7, 7, 6],
si$[6, 7, 10, 7, 6]
]
for test: si in ssi$elements(tests) do
stream$puts(po, int$unparse(water(test)) || " ")
end
end start_up</syntaxhighlight>
{{out}}
<pre>2 14 35 0 0 0 0</pre>
=={{header|Cowgol}}==
<syntaxhighlight lang="cowgol">include "cowgol.coh";
include "argv.coh";
# Count the amount of water in a given array
sub water(towers: [uint8], length: intptr): (units: uint8) is
units := 0;
loop
var right := towers + length;
loop
right := @prev right;
if right < towers or [right] != 0 then
break;
end if;
end loop;
if right < towers then break; end if;
var blocks: uint8 := 0;
var col := towers;
while col <= right loop
if [col] != 0 then
[col] := [col] - 1;
blocks := blocks + 1;
elseif blocks != 0 then
units := units + 1;
end if;
col := @next col;
end loop;
if blocks < 2 then
break;
end if;
end loop;
end sub;
# Read list from the command line and print the answer
ArgvInit();
var towers: uint8[256];
var count: @indexof towers := 0;
var n32: int32;
loop
var argmt := ArgvNext();
if argmt == 0 as [uint8] then
break;
end if;
(n32, argmt) := AToI(argmt);
towers[count] := n32 as uint8;
count := count + 1;
end loop;
if count == 0 then
print("enter towers on command line\n");
ExitWithError();
end if;
print_i8(water(&towers[0], count as intptr));
print_nl();</syntaxhighlight>
{{out}}
<pre>$ ./water.386 1 5 3 7 2
2
$ ./water.386 5 3 7 2 6 4 5 9 1 2
14
$ ./water.386 2 6 3 5 2 8 1 4 2 2 5 3 5 7 4 1
35
$ ./water.386 5 5 5 5
0
$ ./water.386 5 6 7 8
0
$ ./water.386 8 7 7 6
0
$ ./water.386 6 7 10 7 6
0</pre>
=={{header|D}}==
{{Trans|C#}}
<syntaxhighlight lang="d">import std.stdio;
void main() {
int i = 1;
int[][] tba = [
[ 1, 5, 3, 7, 2 ],
[ 5, 3, 7, 2, 6, 4, 5, 9, 1, 2 ],
[ 2, 6, 3, 5, 2, 8, 1, 4, 2, 2, 5, 3, 5, 7, 4, 1 ],
[ 5, 5, 5, 5 ],
[ 5, 6, 7, 8 ],
[ 8, 7, 7, 6 ],
[ 6, 7, 10, 7, 6 ]
];
foreach (tea; tba) {
int rht, wu, bof;
do {
for (rht = tea.length - 1; rht >= 0; rht--) {
if (tea[rht] > 0) {
break;
}
}
if (rht < 0) {
break;
}
bof = 0;
for (int col = 0; col <= rht; col++) {
if (tea[col] > 0) {
tea[col] -= 1; bof += 1;
} else if (bof > 0) {
wu++;
}
}
if (bof < 2) {
break;
}
} while (true);
write("Block ", i++);
if (wu == 0) {
write(" does not hold any");
} else {
write(" holds ", wu);
}
writeln(" water units.");
}
}</syntaxhighlight>
{{out}}
<pre>Block 1 holds 2 water units.
Block 2 holds 14 water units.
Block 3 holds 35 water units.
Block 4 does not hold any water units.
Block 5 does not hold any water units.
Block 6 does not hold any water units.
Block 7 does not hold any water units.</pre>
=={{header|Delphi}}==
{{works with|Delphi|6.0}}
{{libheader|SysUtils,StdCtrls}}
The program builds a matrix of the towers and scans each line looking for pairs of towers that trap water.
<syntaxhighlight lang="Delphi">
var Towers1: array [0..4] of integer = (1, 5, 3, 7, 2);
var Towers2: array [0..9] of integer = (5, 3, 7, 2, 6, 4, 5, 9, 1, 2);
var Towers3: array [0..15] of integer = (2, 6, 3, 5, 2, 8, 1, 4, 2, 2, 5, 3, 5, 7, 4, 1);
var Towers4: array [0..3] of integer = (5, 5, 5, 5);
var Towers5: array [0..3] of integer = (5, 6, 7, 8);
var Towers6: array [0..3] of integer = (8, 7, 7, 6);
var Towers7: array [0..4] of integer = (6, 7, 10, 7, 6);
type TMatrix = array of array of boolean;
function ArrayToMatrix(Towers: array of integer): TMatrix;
{Convert Tower Array to Matrix for analysis}
var Max,I,X,Y: integer;
begin
Max:=0;
for I:=0 to High(Towers) do if Towers[I]>=Max then Max:=Towers[I];
SetLength(Result,Length(Towers),Max);
for Y:=0 to High(Result[0]) do
for X:=0 to High(Result) do Result[X,Y]:=Towers[X]>(Max-Y);
end;
procedure DisplayMatrix(Memo: TMemo; Matrix: TMatrix);
{Display a matrix}
var X,Y: integer;
var S: string;
begin
for Y:=0 to High(Matrix[0]) do
begin
S:='[';
for X:=0 to High(Matrix) do
begin
if Matrix[X,Y] then S:=S+'#'
else S:=S+' ';
end;
S:=S+']';
Memo.Lines.Add(S);
end;
end;
function GetWaterStorage(Matrix: TMatrix): integer;
{Analyze matrix to get water storage amount}
var X,Y,Cnt: integer;
var Inside: boolean;
begin
Result:=0;
{Scan each row of matrix to see if it is storing water}
for Y:=0 to High(Matrix[0]) do
begin
Inside:=False;
Cnt:=0;
for X:=0 to High(Matrix) do
begin
{Test if this is a tower}
if Matrix[X,Y] then
begin
{if so, we may be inside trough}
Inside:=True;
{If Cnt>0 there was a previous tower}
{And we've impounded water }
Result:=Result+Cnt;
{Start new count with new tower}
Cnt:=0;
end
else if Inside then Inc(Cnt); {Count potential impounded water}
end;
end;
end;
procedure ShowWaterLevels(Memo: TMemo; Towers: array of integer);
{Analyze the water storage of towers and display result}
var Water: integer;
var Matrix: TMatrix;
begin
Matrix:=ArrayToMatrix(Towers);
DisplayMatrix(Memo,Matrix);
Water:=GetWaterStorage(Matrix);
Memo.Lines.Add('Storage: '+IntToStr(Water)+CRLF);
end;
procedure WaterLevel(Memo: TMemo);
begin
ShowWaterLevels(Memo,Towers1);
ShowWaterLevels(Memo,Towers2);
ShowWaterLevels(Memo,Towers3);
ShowWaterLevels(Memo,Towers4);
ShowWaterLevels(Memo,Towers5);
ShowWaterLevels(Memo,Towers6);
ShowWaterLevels(Memo,Towers7);
end;
</syntaxhighlight>
{{out}}
<pre>
[ ]
[ # ]
[ # ]
[ # # ]
[ # # ]
[ ### ]
[ ####]
Storage: 2
[ ]
[ # ]
[ # ]
[ # # ]
[ # # # ]
[# # # ## ]
[# # #### ]
[### #### ]
[######## #]
Storage: 14
[ ]
[ # ]
[ # # ]
[ # # # ]
[ # # # # ## ]
[ # # # # # ### ]
[ ### # # ##### ]
[###### ######## ]
Storage: 35
[ ]
[####]
[####]
[####]
[####]
Storage: 0
[ ]
[ #]
[ ##]
[ ###]
[####]
[####]
[####]
[####]
Storage: 0
[ ]
[# ]
[### ]
[####]
[####]
[####]
[####]
[####]
Storage: 0
[ ]
[ # ]
[ # ]
[ # ]
[ ### ]
[#####]
[#####]
[#####]
[#####]
[#####]
Storage: 0
Elapsed Time: 171.444 ms.
</pre>
=={{header|EasyLang}}==
<syntaxhighlight lang="easylang">
proc water h[] . .
n = len h[]
len left[] n
len right[] n
for i = 1 to n
max = higher max h[i]
left[i] = max
.
max = 0
for i = n downto 1
max = higher max h[i]
right[i] = max
.
for i = 1 to n
sum += (lower left[i] right[i]) - h[i]
.
print sum
.
repeat
s$ = input
until s$ = ""
water number strsplit s$ " "
.
#
input_data
1 5 3 7 2
5 3 7 2 6 4 5 9 1 2
2 6 3 5 2 8 1 4 2 2 5 3 5 7 4 1
5 5 5 5
5 6 7 8
8 7 7 6
6 7 10 7 6
</syntaxhighlight>
=={{header|Erlang}}==
Implements a version that uses recursion to solve the problem functionally, using two passes without requiring list reversal or modifications. On the list iteration from head to tail, gather the largest element seen so far (being the highest one on the left). Once the list is scanned, each position returns the highest tower to its right as reported by its follower, along with the amount of water seen so far, which can then be used to calculate the value at the current position. Back at the first list element, the final result is gathered.
<syntaxhighlight lang="erlang">
-module(watertowers).
-export([towers/1, demo/0]).
towers(List) -> element(2, tower(List, 0)).
tower([], _) -> {0,0};
tower([H|T], MaxLPrev) ->
MaxL = max(MaxLPrev, H),
{MaxR, WaterAcc} = tower(T, MaxL),
{max(MaxR,H), WaterAcc+max(0, min(MaxR,MaxL)-H)}.
demo() ->
Cases = [[1, 5, 3, 7, 2],
[5, 3, 7, 2, 6, 4, 5, 9, 1, 2],
[2, 6, 3, 5, 2, 8, 1, 4, 2, 2, 5, 3, 5, 7, 4, 1],
[5, 5, 5, 5],
[5, 6, 7, 8],
[8, 7, 7, 6],
[6, 7, 10, 7, 6]],
[io:format("~p -> ~p~n", [Case, towers(Case)]) || Case <- Cases],
ok.
</syntaxhighlight>
{{out}}
<pre>
1> watertowers:demo().
[1,5,3,7,2] -> 2
[5,3,7,2,6,4,5,9,1,2] -> 14
[2,6,3,5,2,8,1,4,2,2,5,3,5,7,4,1] -> 35
[5,5,5,5] -> 0
[5,6,7,8] -> 0
[8,7,7,6] -> 0
[6,7,10,7,6] -> 0
ok
</pre>
=={{header|F_Sharp|F#}}==
see http://stackoverflow.com/questions/24414700/water-collected-between-towers/43779936#43779936 for an explanation of this code. It is proportional to the number of towers. Although the examples on stackoverflow claim this, the n they use is actually the distance between the two end towers and not the number of towers. Consider the case of a tower of height 5 at 1, a tower of height 10 at 39, and a tower of height 3 at 101.
<syntaxhighlight lang="fsharp">
(*
A solution I'd show to Euclid !!!!.
Nigel Galloway May 4th., 2017
*)
let solve n =
let (n,_)::(i,e)::g = n|>List.sortBy(fun n->(-(snd n)))
let rec fn i g e l =
match e with
| (n,e)::t when n < i -> fn n g t (l+(i-n-1)*e)
| (n,e)::t when n > g -> fn i n t (l+(n-g-1)*e)
| (n,t)::e -> fn i g e (l-t)
| _ -> l
fn (min n i) (max n i) g (e*(abs(n-i)-1))
</syntaxhighlight>
{{out}}
<pre>
solve [(1,1);(2,5);(3,3);(4,7);(5,2)] -> 2
solve [(1,5);(2,3);(3,7);(4,2);(5,6);(6,4);(7,5);(8,9);(9,1);(10,2)] -> 14
solve [(1,2);(2,6);(3,3);(4,5);(5,2);(6,8);(7,1);(8,4);(9,2);(10,2);(11,5);(12,3);(13,5);(14,7);(15,4);(16,1)] -> 35
solve [(1,5);(2,5);(3,5);(4,5)] -> 0
solve [(1,5);(2,6);(3,7);(4,8)] -> 0
solve [(1,8);(2,7);(3,7);(4,6)] -> 0
solve [(1,6);(2,7);(3,10);(4,7);(5,6)] -> 0
solve [(1,5);(39,10);(101,3)] -> 368
</pre>
=={{header|Factor}}==
<syntaxhighlight lang="factor">USING: formatting kernel math.statistics math.vectors sequences ;
: area ( seq -- n )
[ cum-max ] [ <reversed> cum-max reverse vmin ] [ v- sum ] tri ;
{
{ 1 5 3 7 2 }
{ 5 3 7 2 6 4 5 9 1 2 }
{ 2 6 3 5 2 8 1 4 2 2 5 3 5 7 4 1 }
{ 5 5 5 5 }
{ 5 6 7 8 }
{ 8 7 7 6 }
{ 6 7 10 7 6 }
} [ dup area "%[%d, %] -> %d\n" printf ] each</syntaxhighlight>
{{out}}
<pre>
{ 1, 5, 3, 7, 2 } -> 2
{ 5, 3, 7, 2, 6, 4, 5, 9, 1, 2 } -> 14
{ 2, 6, 3, 5, 2, 8, 1, 4, 2, 2, 5, 3, 5, 7, 4, 1 } -> 35
{ 5, 5, 5, 5 } -> 0
{ 5, 6, 7, 8 } -> 0
{ 8, 7, 7, 6 } -> 0
{ 6, 7, 10, 7, 6 } -> 0
</pre>
=={{header|Go}}==
<syntaxhighlight lang="go">
package main
Line 378 ⟶ 2,341:
fmt.Println(waterCollected([]int{8, 7, 7, 6}))
fmt.Println(waterCollected([]int{6, 7, 10, 7, 6}))
}</
{{out}}
Line 391 ⟶ 2,354:
</pre>
=={{header|Groovy}}==
<syntaxhighlight lang="groovy">
Integer waterBetweenTowers(List<Integer> towers) {
// iterate over the vertical axis. There the amount of water each row can hold is
// the number of empty spots, minus the empty spots at the beginning and end
return (1..towers.max()).collect { height ->
// create a string representing the row, '#' for tower material and ' ' for air
// use .trim() to remove spaces at beginning and end and then count remaining spaces
towers.collect({ it >= height ? "#" : " " }).join("").trim().count(" ")
}.sum()
}
tasks = [
[1, 5, 3, 7, 2],
[5, 3, 7, 2, 6, 4, 5, 9, 1, 2],
[2, 6, 3, 5, 2, 8, 1, 4, 2, 2, 5, 3, 5, 7, 4, 1],
[5, 5, 5, 5],
[5, 6, 7, 8],
[8, 7, 7, 6],
[6, 7, 10, 7, 6]
]
tasks.each {
println "$it => total water: ${waterBetweenTowers it}"
}
</syntaxhighlight>
{{out}}
<pre>
[1, 5, 3, 7, 2] => total water: 2
[5, 3, 7, 2, 6, 4, 5, 9, 1, 2] => total water: 14
[2, 6, 3, 5, 2, 8, 1, 4, 2, 2, 5, 3, 5, 7, 4, 1] => total water: 35
[5, 5, 5, 5] => total water: 0
[5, 6, 7, 8] => total water: 0
[8, 7, 7, 6] => total water: 0
[6, 7, 10, 7, 6] => total water: 0
</pre>
=={{header|Haskell}}==
Following the approach of slightly modified [http://stackoverflow.com/users/1416525/cdk cdk]'s Haskell solution at [http://stackoverflow.com/questions/24414700/amazon-water-collected-between-towers/ Stack Overflow]. As recommended in [http://h2.jaguarpaw.co.uk/posts/data-structures-matter/ Programming as if the Correct Data Structure (and Performance) Mattered] it uses [http://hackage.haskell.org/package/vector-0.12.0.1/docs/Data-Vector-Unboxed.html Vector] instead of Array:
<syntaxhighlight lang="haskell">import Data.Vector.Unboxed (Vector)
import qualified Data.Vector.Unboxed as V
waterCollected :: Vector Int -> Int
waterCollected =
V.sum . -- Sum of the water depths over each of
V.filter (> 0) . -- the columns that are covered by some water.
(V.zipWith (-) =<< -- Where coverages are differences between:
(V.zipWith min .
V.scanr1 max)) -- highest wall to right.
main :: IO ()
main =
mapM_
(print . waterCollected . V.fromList)
[ [1, 5, 3, 7, 2]
, [5, 3, 7, 2, 6, 4, 5, 9, 1, 2]
Line 421 ⟶ 2,420:
, [8, 7, 7, 6]
, [6, 7, 10, 7, 6]
]</
{{Out}}
<pre>2
Line 431 ⟶ 2,429:
0
0</pre>
Or, using Data.List for simplicity - no need to prioritize performance here - and adding diagrams:
<syntaxhighlight lang="haskell">import Data.List (replicate, transpose)
-------------- WATER COLLECTED BETWEEN TOWERS ------------
towerPools :: [Int] -> [(Int, Int)]
towerPools =
zipWith min . scanl1 max <*> scanr1 max
>>= zipWith ((<*>) (,) . (-))
--------------------------- TEST -------------------------
main :: IO ()
main =
mapM_
(putStrLn . display . towerPools)
[ [1, 5, 3, 7, 2],
[5, 3, 7, 2, 6, 4, 5, 9, 1, 2],
[2, 6, 3, 5, 2, 8, 1, 4, 2, 2, 5, 3, 5, 7, 4, 1],
[5, 5, 5, 5],
[5, 6, 7, 8],
[8, 7, 7, 6],
[6, 7, 10, 7, 6]
]
------------------------- DIAGRAMS -----------------------
display :: [(Int, Int)] -> String
display = (<>) . showTowers <*> (('\n' :) . showLegend)
showTowers :: [(Int, Int)] -> String
showTowers xs =
let upper = maximum (fst <$> xs)
in '\n' :
( unlines
. transpose
. fmap
( \(x, d) ->
concat $
replicate (upper - (x + d)) " "
<> replicate d "x"
<> replicate x "█"
)
)
xs
showLegend :: [(Int, Int)] -> String
showLegend =
((<>) . show . fmap fst)
<*> ((" -> " <>) . show . foldr ((+) . snd) 0)</syntaxhighlight>
{{Out}}
<pre>
█
█
█x█
█x█
███
████
█████
[1,5,3,7,2] -> 2
█
█
█xxxx█
█x█xx█
█x█x█x██
█x█x████
███x████
████████x█
██████████
[5,3,7,2,6,4,5,9,1,2] -> 14
█
█xxxxxxx█
█xxx█xxxxxxx█
█x█x█xxxx█x██
█x█x█x█xx█x███
███x█x█xx█████
██████x████████
████████████████
[2,6,3,5,2,8,1,4,2,2,5,3,5,7,4,1] -> 35
████
████
████
████
████
[5,5,5,5] -> 0
█
██
███
████
████
████
████
████
[5,6,7,8] -> 0
█
███
████
████
████
████
████
████
[8,7,7,6] -> 0
█
█
█
███
█████
█████
█████
█████
█████
█████
[6,7,10,7,6] -> 0</pre>
=={{header|J}}==
Inspired by [[#Julia]].
'''Solution:'''
<syntaxhighlight lang="j">collectLevels =: >./\ <. >./\. NB. collect levels after filling
waterLevels=: collectLevels - ] NB. water levels for each tower
collectedWater=: +/@waterLevels NB. sum the units of water collected
printTowers =: ' ' , [: |.@|: '#~' #~ ] ,. waterLevels NB. print a nice graph of towers and water</syntaxhighlight>
'''Examples:'''
<syntaxhighlight lang="j"> collectedWater 5 3 7 2 6 4 5 9 1 2
14
printTowers 5 3 7 2 6 4 5 9 1 2
#
#
#~~~~#
#~#~~#
#~#~#~##
#~#~####
###~####
########~#
##########
NB. Test cases
TestTowers =: <@".;._2 noun define
1 5 3 7 2
5 3 7 2 6 4 5 9 1 2
2 6 3 5 2 8 1 4 2 2 5 3 5 7 4 1
5 5 5 5
5 6 7 8
8 7 7 6
6 7 10 7 6
)
TestResults =: 2 14 35 0 0 0 0
TestResults -: collectedWater &> TestTowers NB. check tests
1</syntaxhighlight>
=={{header|Java}}==
{{trans|D}}
<syntaxhighlight lang="java">public class WaterBetweenTowers {
public static void main(String[] args) {
int i = 1;
int[][] tba = new int[][]{
new int[]{1, 5, 3, 7, 2},
new int[]{5, 3, 7, 2, 6, 4, 5, 9, 1, 2},
new int[]{2, 6, 3, 5, 2, 8, 1, 4, 2, 2, 5, 3, 5, 7, 4, 1},
new int[]{5, 5, 5, 5},
new int[]{5, 6, 7, 8},
new int[]{8, 7, 7, 6},
new int[]{6, 7, 10, 7, 6}
};
for (int[] tea : tba) {
int rht, wu = 0, bof;
do {
for (rht = tea.length - 1; rht >= 0; rht--) {
if (tea[rht] > 0) {
break;
}
}
if (rht < 0) {
break;
}
bof = 0;
for (int col = 0; col <= rht; col++) {
if (tea[col] > 0) {
tea[col]--;
bof += 1;
} else if (bof > 0) {
wu++;
}
}
if (bof < 2) {
break;
}
} while (true);
System.out.printf("Block %d", i++);
if (wu == 0) {
System.out.print(" does not hold any");
} else {
System.out.printf(" holds %d", wu);
}
System.out.println(" water units.");
}
}
}</syntaxhighlight>
{{out}}
<pre>Block 1 holds 2 water units.
Block 2 holds 14 water units.
Block 3 holds 35 water units.
Block 4 does not hold any water units.
Block 5 does not hold any water units.
Block 6 does not hold any water units.
Block 7 does not hold any water units.
</pre>
=={{header|JavaScript}}==
===ES5===
{{Trans|Haskell}}
<
'use strict';
Line 526 ⟶ 2,754:
//--> [2, 14, 35, 0, 0, 0, 0]
})();</
{{Out}}
<
===ES6===
{{Trans|Haskell}}
<syntaxhighlight lang="javascript">(() => {
"use strict";
// --------- WATER COLLECTED BETWEEN TOWERS ----------
// waterCollected :: [Int] -> Int
const waterCollected = xs =>
scanl1(max)(xs)
)(
scanr1(max)(xs)
)
)
));
// ---------------------- TEST -----------------------
const main = () => [
[1, 5, 3, 7, 2],
[5, 3, 7, 2, 6, 4, 5, 9, 1, 2],
[2, 6, 3, 5, 2, 8, 1, 4, 2, 2, 5, 3, 5, 7, 4, 1],
[5, 5, 5, 5],
[5, 6, 7, 8],
[8, 7, 7, 6],
[6, 7, 10, 7, 6]
].map(waterCollected);
// --------------------- GENERIC ---------------------
// Tuple (,) :: a -> b -> (a, b)
"0": a,
"1": b,
length: 2
});
//
const
xs =>
//
const
b => a < b;
// max :: Ord a => a -> a -> a
const max =
// b if its greater than a,
// otherwise a.
b => a > b ? a : b;
// min :: Ord a => a -> a -> a
const min =
b => b < a ? b : a;
// scanl :: (b -> a -> b) -> b -> [a] -> [b]
const scanl = f => startValue => xs =>
return Tuple(v)(a[1].concat(v));
}, Tuple(startValue)([startValue]))[1];
// scanl1 :: (a -> a -> a) -> [a] -> [a]
const scanl1 = f =>
// scanl1 is a variant of scanl that
// has no starting value argument.
xs => xs.length > 0 ? (
scanl(f)(
xs[0]
)(xs.slice(1))
) : [];
// scanr :: (a -> b -> b) -> b -> [a] -> [b]
const scanr = f =>
startValue => xs => xs.reduceRight(
(a, x) => {
const v = f(x)(a[0]);
return Tuple(v)([v].concat(a[1]));
}, Tuple(startValue)([startValue])
)[1];
// scanr1 :: (a -> a -> a) -> [a] -> [a]
const scanr1 = f =>
// scanr1 is a variant of scanr that has no
// seed-value argument, and assumes that
// xs is not empty.
xs => xs.length > 0 ? (
scanr(f)(
xs.slice(-1)[0]
)(xs.slice(0, -1))
) : [];
// subtract :: Num -> Num -> Num
const subtract = x =>
y => y - x;
// sum :: [Num] -> Num
const sum = xs =>
// The numeric sum of all values in xs.
xs.reduce((a, x) => a + x, 0);
// zipWith :: (a -> b -> c) -> [a] -> [b] -> [c]
const zipWith = f =>
// A list constructed by zipping with a
// custom function, rather than with the
// default tuple constructor.
xs => ys => xs.map(
(x, i) => f(x)(ys[i])
).slice(
0, Math.min(xs.length, ys.length)
);
// MAIN ---
return main();
})();</syntaxhighlight>
{{Out}}
<
=={{header|jq}}==
{{trans|Kotlin}}
{{works with|jq}}
'''Works with gojq, the Go implementation of jq'''
<syntaxhighlight lang="jq">def waterCollected:
. as $tower
| ($tower|length) as $n
| ([0] + [range(1;$n) | ($tower[0:.] | max) ]) as $highLeft
| ( [range(1;$n) | ($tower[.:$n] | max) ] + [0]) as $highRight
| [ range(0;$n) | [ ([$highLeft[.], $highRight[.] ]| min) - $tower[.], 0 ] | max]
| add ;
def towers: [
[1, 5, 3, 7, 2],
[5, 3, 7, 2, 6, 4, 5, 9, 1, 2],
[2, 6, 3, 5, 2, 8, 1, 4, 2, 2, 5, 3, 5, 7, 4, 1],
[5, 5, 5, 5],
[5, 6, 7, 8],
[8, 7, 7, 6],
[6, 7, 10, 7, 6]
];
towers[]
| "\(waterCollected) from \(.)"</syntaxhighlight>
{{out}}
As for [[#Kotlin]] and others.
=={{header|Julia}}==
Inspired to [[#Python]].
<syntaxhighlight lang="julia">using Printf
function watercollected(towers::Vector{Int})
high_lft = vcat(0, accumulate(max, towers[1:end-1]))
high_rgt = vcat(reverse(accumulate(max, towers[end:-1:2])), 0)
waterlvl = max.(min.(high_lft, high_rgt) .- towers, 0)
return waterlvl
end
function towerprint(towers, levels)
ctowers = copy(towers)
clevels = copy(levels)
hmax = maximum(towers)
ntow = length(towers)
for h in hmax:-1:1
@printf("%2i |", h)
for j in 1:ntow
if ctowers[j] + clevels[j] ≥ h
if clevels[j] > 0
cell = "≈≈"
clevels[j] -= 1
else
cell = "NN"
ctowers[j] -= 1
end
else
cell = " "
end
print(cell)
end
println("|")
end
println(" " * join(lpad(t, 2) for t in levels) * ": Water lvl")
println(" " * join(lpad(t, 2) for t in towers) * ": Tower lvl")
end
for towers in [[1, 5, 3, 7, 2], [5, 3, 7, 2, 6, 4, 5, 9, 1, 2],
[2, 6, 3, 5, 2, 8, 1, 4, 2, 2, 5, 3, 5, 7, 4, 1],
[5, 5, 5, 5], [5, 6, 7, 8], [8, 7, 7, 6], [6, 7, 10, 7, 6]]
towerprint(towers, watercollected(towers))
println()
end</syntaxhighlight>
{{out}}
<pre> 7 | NN |
6 | NN |
5 | NN≈≈NN |
4 | NN≈≈NN |
3 | NNNNNN |
2 | NNNNNNNN|
1 |NNNNNNNNNN|
0 0 2 0 0: Water lvl
1 5 3 7 2: Tower lvl
9 | NN |
8 | NN |
7 | NN≈≈≈≈≈≈≈≈NN |
6 | NN≈≈NN≈≈≈≈NN |
5 |NN≈≈NN≈≈NN≈≈NNNN |
4 |NN≈≈NN≈≈NNNNNNNN |
3 |NNNNNN≈≈NNNNNNNN |
2 |NNNNNNNNNNNNNNNN≈≈NN|
1 |NNNNNNNNNNNNNNNNNNNN|
0 2 0 5 1 3 2 0 1 0: Water lvl
5 3 7 2 6 4 5 9 1 2: Tower lvl
8 | NN |
7 | NN≈≈≈≈≈≈≈≈≈≈≈≈≈≈NN |
6 | NN≈≈≈≈≈≈NN≈≈≈≈≈≈≈≈≈≈≈≈≈≈NN |
5 | NN≈≈NN≈≈NN≈≈≈≈≈≈≈≈NN≈≈NNNN |
4 | NN≈≈NN≈≈NN≈≈NN≈≈≈≈NN≈≈NNNNNN |
3 | NNNNNN≈≈NN≈≈NN≈≈≈≈NNNNNNNNNN |
2 |NNNNNNNNNNNN≈≈NNNNNNNNNNNNNNNN |
1 |NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN|
0 0 3 1 4 0 6 3 5 5 2 4 2 0 0 0: Water lvl
2 6 3 5 2 8 1 4 2 2 5 3 5 7 4 1: Tower lvl
5 |NNNNNNNN|
4 |NNNNNNNN|
3 |NNNNNNNN|
2 |NNNNNNNN|
1 |NNNNNNNN|
0 0 0 0: Water lvl
5 5 5 5: Tower lvl
8 | NN|
7 | NNNN|
6 | NNNNNN|
5 |NNNNNNNN|
4 |NNNNNNNN|
3 |NNNNNNNN|
2 |NNNNNNNN|
1 |NNNNNNNN|
0 0 0 0: Water lvl
5 6 7 8: Tower lvl
8 |NN |
7 |NNNNNN |
6 |NNNNNNNN|
5 |NNNNNNNN|
4 |NNNNNNNN|
3 |NNNNNNNN|
2 |NNNNNNNN|
1 |NNNNNNNN|
0 0 0 0: Water lvl
8 7 7 6: Tower lvl
10 | NN |
9 | NN |
8 | NN |
7 | NNNNNN |
6 |NNNNNNNNNN|
5 |NNNNNNNNNN|
4 |NNNNNNNNNN|
3 |NNNNNNNNNN|
2 |NNNNNNNNNN|
1 |NNNNNNNNNN|
0 0 0 0 0: Water lvl
6 710 7 6: Tower lvl
</pre>
=={{header|Kotlin}}==
{{trans|Python}}
<syntaxhighlight lang="scala">// version 1.1.2
fun waterCollected(tower: IntArray): Int {
val n = tower.size
val highLeft = listOf(0) + (1 until n).map { tower.slice(0 until it).max()!! }
val highRight = (1 until n).map { tower.slice(it until n).max()!! } + 0
return (0 until n).map { maxOf(minOf(highLeft[it], highRight[it]) - tower[it], 0) }.sum()
}
fun main(args: Array<String>) {
val towers = listOf(
intArrayOf(1, 5, 3, 7, 2),
intArrayOf(5, 3, 7, 2, 6, 4, 5, 9, 1, 2),
intArrayOf(2, 6, 3, 5, 2, 8, 1, 4, 2, 2, 5, 3, 5, 7, 4, 1),
intArrayOf(5, 5, 5, 5),
intArrayOf(5, 6, 7, 8),
intArrayOf(8, 7, 7, 6),
intArrayOf(6, 7, 10, 7, 6)
)
for (tower in towers) {
println("${"%2d".format(waterCollected(tower))} from ${tower.contentToString()}")
}
}</syntaxhighlight>
{{out}}
<pre>
2 from [1, 5, 3, 7, 2]
14 from [5, 3, 7, 2, 6, 4, 5, 9, 1, 2]
35 from [2, 6, 3, 5, 2, 8, 1, 4, 2, 2, 5, 3, 5, 7, 4, 1]
0 from [5, 5, 5, 5]
0 from [5, 6, 7, 8]
0 from [8, 7, 7, 6]
0 from [6, 7, 10, 7, 6]
</pre>
=={{header|Lua}}==
{{trans|C#}}
<syntaxhighlight lang="lua">function waterCollected(i,tower)
local length = 0
for _ in pairs(tower) do
length = length + 1
end
local wu = 0
repeat
local rht = length - 1
while rht >= 0 do
if tower[rht + 1] > 0 then
break
end
rht = rht - 1
end
if rht < 0 then
break
end
local bof = 0
local col = 0
while col <= rht do
if tower[col + 1] > 0 then
tower[col + 1] = tower[col + 1] - 1
bof = bof + 1
elseif bof > 0 then
wu = wu + 1
end
col = col + 1
end
if bof < 2 then
break
end
until false
if wu == 0 then
print(string.format("Block %d does not hold any water.", i))
else
print(string.format("Block %d holds %d water units.", i, wu))
end
end
function main()
local towers = {
{1, 5, 3, 7, 2},
{5, 3, 7, 2, 6, 4, 5, 9, 1, 2},
{2, 6, 3, 5, 2, 8, 1, 4, 2, 2, 5, 3, 5, 7, 4, 1},
{5, 5, 5, 5},
{5, 6, 7, 8},
{8, 7, 7, 6},
{6, 7, 10, 7, 6}
}
for i,tbl in pairs(towers) do
waterCollected(i,tbl)
end
end
main()</syntaxhighlight>
{{out}}
<pre>Block 1 holds 2 water units.
Block 2 holds 14 water units.
Block 3 holds 35 water units.
Block 4 does not hold any water.
Block 5 does not hold any water.
Block 6 does not hold any water.
Block 7 does not hold any water.</pre>
=={{header|M2000 Interpreter}}==
===Scan min-max for each bar===
<syntaxhighlight lang="m2000 interpreter">
Module Water {
Flush ' empty stack
Data (1, 5, 3, 7, 2)
Data (5, 3, 7, 2, 6, 4, 5, 9, 1, 2)
Data (2, 6, 3, 5, 2, 8, 1, 4, 2, 2, 5, 3, 5, 7, 4, 1)
Data (5, 5, 5, 5), (5, 6, 7, 8),(8, 7, 7, 6)
Data (6, 7, 10, 7, 6)
bars=stack.size ' mark stack frame
Dim bar()
for bar=1 to bars
bar()=Array ' pop an array from stack
acc=0
For i=1 to len(bar())-2
level1=bar(i)
level2=level1
m=each(bar(), i+1, 1)
while m
if array(m)>level1 then level1=array(m)
End While
n=each(bar(), i+1, -1)
while n
if array(n)>level2 then level2=array(n)
End While
acc+=max.data(min(level1, level2)-bar(i), 0)
Next i
Data acc ' push to end value
Next bar
finalwater=[] ' is a stack object
Print finalwater
}
Water
</syntaxhighlight>
===Drain method===
Module Water2 {
Flush ' empty stack
Data (1, 5, 3, 7, 2)
Data (5, 3, 7, 2, 6, 4, 5, 9, 1, 2)
Data (2, 6, 3, 5, 2, 8, 1, 4, 2, 2, 5, 3, 5, 7, 4, 1)
Data (5, 5, 5, 5), (5, 6, 7, 8),(8, 7, 7, 6)
Data (6, 7, 10, 7, 6)
bars=stack.size ' mark stack frame
Dim bar()
For bar=1 to bars
bar()=Array ' pop an array from stack
acc=0
range=bar()#max()-bar()#min()
if range>0 then
dim water(len(bar()))=bar()#max()
water(0)=bar(0)
water(len(bar())-1)=bar(len(bar())-1)
For j=1 to range-1
For i=1 to len(bar())-2
if water(i)>bar(i) then if water(i-1)<water(i) Then water(i)--
Next i
For i=len(bar())-2 to 1
if water(i)>bar(i) then if water(i+1)<water(i) Then water(i)--
Next i
Next j
Data water()#sum()-bar()#sum()
Else
Data 0
End if
Next bar
finalwater=[]
Print finalwater
}
Water2
<syntaxhighlight lang="m2000 interpreter">
</syntaxhighlight>
===Faster Method===
{{trans|AWK}}
<syntaxhighlight lang="m2000 interpreter">
Module Water3 {
Flush ' empty stack
Data (1, 5, 3, 7, 2)
Data (5, 3, 7, 2, 6, 4, 5, 9, 1, 2)
Data (2, 6, 3, 5, 2, 8, 1, 4, 2, 2, 5, 3, 5, 7, 4, 1)
Data (5, 5, 5, 5), (5, 6, 7, 8),(8, 7, 7, 6)
Data (6, 7, 10, 7, 6)
bars=stack.size ' mark stack frame
Dim bar()
for bar=1 to bars
bar()=Array ' pop an array from stack
acc=0
n=len(bar())-1
dim hl(n+1), hr(n+1)
For i=n to 0
hr(i)=max.data(bar(i), if(i<n->hr(i+1), 0))
Next i
For i=0 to n
hl(i)=max.data(bar(i), if(i>0->hl(i-1), 0))
acc+=min.data(hl(i), hr(i))-bar(i)
Next i
Data acc ' push to end value
Next bar
finalwater=[] ' is a stack object
Print finalwater
}
Water3
</syntaxhighlight>
{{out}}
<pre>
2 14 35 0 0 0 0
</pre >
=={{header|Mathematica}} / {{header|Wolfram Language}}==
<syntaxhighlight lang="mathematica">ClearAll[waterbetween]
waterbetween[h_List] := Module[{mi, ma, ch},
{mi, ma} = MinMax[h];
Sum[
ch = h - i;
Count[
Flatten@
Position[
ch, _?Negative], _?(Between[
MinMax[Position[ch, _?NonNegative]]])]
,
{i, mi + 1, ma}
]
]
h = {{1, 5, 3, 7, 2}, {5, 3, 7, 2, 6, 4, 5, 9, 1, 2}, {2, 6, 3, 5, 2,
8, 1, 4, 2, 2, 5, 3, 5, 7, 4, 1}, {5, 5, 5, 5}, {5, 6, 7, 8}, {8,
7, 7, 6}, {6, 7, 10, 7, 6}};
waterbetween /@ h</syntaxhighlight>
{{out}}
<pre>{2, 14, 35, 0, 0, 0, 0}</pre>
=={{header|Nim}}==
<syntaxhighlight lang="nim">import math, sequtils, sugar
proc water(barChart: seq[int], isLeftPeak = false, isRightPeak = false): int =
if len(barChart) <= 2:
return
if isLeftPeak and isRightPeak:
return sum(barChart[1..^2].map(x=>min(barChart[0], barChart[^1])-x))
var i: int
if isLeftPeak:
i = maxIndex(barChart[1..^1])+1
else:
i = maxIndex(barChart[0..^2])
return water(barChart[0..i], isLeftPeak, true)+water(barChart[i..^1], true, isRightPeak)
const barCharts = [
@[1, 5, 3, 7, 2],
@[5, 3, 7, 2, 6, 4, 5, 9, 1, 2],
@[2, 6, 3, 5, 2, 8, 1, 4, 2, 2, 5, 3, 5, 7, 4, 1],
@[5, 5, 5, 5],
@[5, 6, 7, 8],
@[8, 7, 7, 6],
@[6, 7, 10, 7, 6]]
const waterUnits = barCharts.map(chart=>water(chart, false, false))
echo(waterUnits)
</syntaxhighlight>
{{out}}
<pre>
@[2, 14, 35, 0, 0, 0, 0]
</pre >
=={{header|Pascal}}==
{{works with|Delphi|7}}
{{works with|Free Pascal}}
<syntaxhighlight lang="pascal">
program RainInFlatland;
{$IFDEF FPC} // Free Pascal
{$MODE Delphi}
{$ELSE} // Delphi
{$APPTYPE CONSOLE}
{$ENDIF}
uses SysUtils;
type THeight = integer;
// Heights could be f.p., but some changes to the code would be needed:
// (1) the inc function isn't available for f.p. values,
// (2) the print-out would need extra formatting.
{------------------------------------------------------------------------------
Find highest tower; if there are 2 or more equal highest, choose any.
Then fill troughs so that on going towards the highest tower, from the
left-hand or right-hand end, there are no steps down.
Amount of filling required equals amount of water collected.
}
function FillTroughs( const h : array of THeight) : THeight;
var
m, i, i_max : integer;
h_max : THeight;
begin
result := 0;
m := High( h); // highest index, 0-based; there are m + 1 towers
if (m <= 1) then exit; // result = 0 if <= 2 towers
// Find highest tower and its index in the array.
h_max := h[0];
i_max := 0;
for i := 1 to m do begin
if h[i] > h_max then begin
h_max := h[i];
i_max := i;
end;
end;
// Fill troughs from left-hand end to highest tower
h_max := h[0];
for i := 1 to i_max - 1 do begin
if h[i] < h_max then inc( result, h_max - h[i])
else h_max := h[i];
end;
// Fill troughs from right-hand end to highest tower
h_max := h[m];
for i := m - 1 downto i_max + 1 do begin
if h[i] < h_max then inc( result, h_max - h[i])
else h_max := h[i];
end;
end;
{-------------------------------------------------------------------------
Wrapper for the above: finds amount of water, and prints input and result.
}
procedure CalcAndPrint( h : array of THeight);
var
water : THeight;
j : integer;
begin
water := FillTroughs( h);
Write( water:5, ' <-- [');
for j := 0 to High( h) do begin
Write( h[j]);
if j < High(h) then Write(', ') else WriteLn(']');
end;
end;
{---------------------------------------------------------------------------
Main routine.
}
begin
CalcAndPrint([1,5,3,7,2]);
CalcAndPrint([5,3,7,2,6,4,5,9,1,2]);
CalcAndPrint([2,6,3,5,2,8,1,4,2,2,5,3,5,7,4,1]);
CalcAndPrint([5,5,5,5]);
CalcAndPrint([5,6,7,8]);
CalcAndPrint([8,7,7,6]);
CalcAndPrint([6,7,10,7,6]);
end.
</syntaxhighlight>
{{out}}
<pre>
2 <-- [1, 5, 3, 7, 2]
14 <-- [5, 3, 7, 2, 6, 4, 5, 9, 1, 2]
35 <-- [2, 6, 3, 5, 2, 8, 1, 4, 2, 2, 5, 3, 5, 7, 4, 1]
0 <-- [5, 5, 5, 5]
0 <-- [5, 6, 7, 8]
0 <-- [8, 7, 7, 6]
0 <-- [6, 7, 10, 7, 6]
</pre>
=={{header|Perl}}==
<
use List::Util qw{ min max sum };
Line 644 ⟶ 3,438:
[ 8, 7, 7, 6 ],
[ 6, 7, 10, 7, 6 ],
);</
{{Out}}
<pre>2 14 35 0 0 0 0</pre>
=={{header|
=== inefficient one-pass method ===
<!--<syntaxhighlight lang="phix">(phixonline)-->
<span style="color: #008080;">with</span> <span style="color: #008080;">javascript_semantics</span>
<span style="color: #008080;">function</span> <span style="color: #000000;">collect_water</span><span style="color: #0000FF;">(</span><span style="color: #004080;">sequence</span> <span style="color: #000000;">heights</span><span style="color: #0000FF;">)</span>
<span style="color: #004080;">integer</span> <span style="color: #000000;">res</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">0</span>
<span style="color: #008080;">for</span> <span style="color: #000000;">i</span><span style="color: #0000FF;">=</span><span style="color: #000000;">2</span> <span style="color: #008080;">to</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">heights</span><span style="color: #0000FF;">)-</span><span style="color: #000000;">1</span> <span style="color: #008080;">do</span>
<span style="color: #004080;">integer</span> <span style="color: #000000;">lm</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">max</span><span style="color: #0000FF;">(</span><span style="color: #000000;">heights</span><span style="color: #0000FF;">[</span><span style="color: #000000;">1</span><span style="color: #0000FF;">..</span><span style="color: #000000;">i</span><span style="color: #0000FF;">-</span><span style="color: #000000;">1</span><span style="color: #0000FF;">]),</span>
<span style="color: #000000;">rm</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">max</span><span style="color: #0000FF;">(</span><span style="color: #000000;">heights</span><span style="color: #0000FF;">[</span><span style="color: #000000;">i</span><span style="color: #0000FF;">+</span><span style="color: #000000;">1</span><span style="color: #0000FF;">..$]),</span>
<span style="color: #000000;">d</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">min</span><span style="color: #0000FF;">(</span><span style="color: #000000;">lm</span><span style="color: #0000FF;">,</span><span style="color: #000000;">rm</span><span style="color: #0000FF;">)-</span><span style="color: #000000;">heights</span><span style="color: #0000FF;">[</span><span style="color: #000000;">i</span><span style="color: #0000FF;">]</span>
<span style="color: #000000;">res</span> <span style="color: #0000FF;">+=</span> <span style="color: #7060A8;">max</span><span style="color: #0000FF;">(</span><span style="color: #000000;">0</span><span style="color: #0000FF;">,</span><span style="color: #000000;">d</span><span style="color: #0000FF;">)</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">for</span>
<span style="color: #008080;">return</span> <span style="color: #000000;">res</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">function</span>
<span style="color: #008080;">constant</span> <span style="color: #000000;">tests</span> <span style="color: #0000FF;">=</span> <span style="color: #0000FF;">{{</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #000000;">5</span><span style="color: #0000FF;">,</span><span style="color: #000000;">3</span><span style="color: #0000FF;">,</span><span style="color: #000000;">7</span><span style="color: #0000FF;">,</span><span style="color: #000000;">2</span><span style="color: #0000FF;">},</span>
<span style="color: #0000FF;">{</span><span style="color: #000000;">5</span><span style="color: #0000FF;">,</span><span style="color: #000000;">3</span><span style="color: #0000FF;">,</span><span style="color: #000000;">7</span><span style="color: #0000FF;">,</span><span style="color: #000000;">2</span><span style="color: #0000FF;">,</span><span style="color: #000000;">6</span><span style="color: #0000FF;">,</span><span style="color: #000000;">4</span><span style="color: #0000FF;">,</span><span style="color: #000000;">5</span><span style="color: #0000FF;">,</span><span style="color: #000000;">9</span><span style="color: #0000FF;">,</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #000000;">2</span><span style="color: #0000FF;">},</span>
<span style="color: #0000FF;">{</span><span style="color: #000000;">2</span><span style="color: #0000FF;">,</span><span style="color: #000000;">6</span><span style="color: #0000FF;">,</span><span style="color: #000000;">3</span><span style="color: #0000FF;">,</span><span style="color: #000000;">5</span><span style="color: #0000FF;">,</span><span style="color: #000000;">2</span><span style="color: #0000FF;">,</span><span style="color: #000000;">8</span><span style="color: #0000FF;">,</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #000000;">4</span><span style="color: #0000FF;">,</span><span style="color: #000000;">2</span><span style="color: #0000FF;">,</span><span style="color: #000000;">2</span><span style="color: #0000FF;">,</span><span style="color: #000000;">5</span><span style="color: #0000FF;">,</span><span style="color: #000000;">3</span><span style="color: #0000FF;">,</span><span style="color: #000000;">5</span><span style="color: #0000FF;">,</span><span style="color: #000000;">7</span><span style="color: #0000FF;">,</span><span style="color: #000000;">4</span><span style="color: #0000FF;">,</span><span style="color: #000000;">1</span><span style="color: #0000FF;">},</span>
<span style="color: #0000FF;">{</span><span style="color: #000000;">5</span><span style="color: #0000FF;">,</span><span style="color: #000000;">5</span><span style="color: #0000FF;">,</span><span style="color: #000000;">5</span><span style="color: #0000FF;">,</span><span style="color: #000000;">5</span><span style="color: #0000FF;">},</span>
<span style="color: #0000FF;">{</span><span style="color: #000000;">5</span><span style="color: #0000FF;">,</span><span style="color: #000000;">6</span><span style="color: #0000FF;">,</span><span style="color: #000000;">7</span><span style="color: #0000FF;">,</span><span style="color: #000000;">8</span><span style="color: #0000FF;">},</span>
<span style="color: #0000FF;">{</span><span style="color: #000000;">8</span><span style="color: #0000FF;">,</span><span style="color: #000000;">7</span><span style="color: #0000FF;">,</span><span style="color: #000000;">7</span><span style="color: #0000FF;">,</span><span style="color: #000000;">6</span><span style="color: #0000FF;">},</span>
<span style="color: #0000FF;">{</span><span style="color: #000000;">6</span><span style="color: #0000FF;">,</span><span style="color: #000000;">7</span><span style="color: #0000FF;">,</span><span style="color: #000000;">10</span><span style="color: #0000FF;">,</span><span style="color: #000000;">7</span><span style="color: #0000FF;">,</span><span style="color: #000000;">6</span><span style="color: #0000FF;">}}</span>
<span style="color: #008080;">for</span> <span style="color: #000000;">i</span><span style="color: #0000FF;">=</span><span style="color: #000000;">1</span> <span style="color: #008080;">to</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">tests</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">do</span>
<span style="color: #004080;">sequence</span> <span style="color: #000000;">ti</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">tests</span><span style="color: #0000FF;">[</span><span style="color: #000000;">i</span><span style="color: #0000FF;">]</span>
<span style="color: #7060A8;">printf</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"%35s : %d\n"</span><span style="color: #0000FF;">,{</span><span style="color: #7060A8;">sprint</span><span style="color: #0000FF;">(</span><span style="color: #000000;">ti</span><span style="color: #0000FF;">),</span><span style="color: #000000;">collect_water</span><span style="color: #0000FF;">(</span><span style="color: #000000;">ti</span><span style="color: #0000FF;">)})</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">for</span>
<!--</syntaxhighlight>-->
{{out}}
<pre>
{1,5,3,7,2} : 2
{5,3,7,2,6,4,5,9,1,2} : 14
{2,6,3,5,2,8,1,4,2,2,5,3,5,7,4,1} : 35
{5,5,5,5} : 0
{5,6,7,8} : 0
{8,7,7,6} : 0
{6,7,10,7,6} : 0
</pre>
=== more efficient two-pass version ===
<!--<syntaxhighlight lang="phix">(phixonline)-->
<span style="color: #008080;">with</span> <span style="color: #008080;">javascript_semantics</span>
<span style="color: #008080;">function</span> <span style="color: #000000;">collect_water</span><span style="color: #0000FF;">(</span><span style="color: #004080;">sequence</span> <span style="color: #000000;">heights</span><span style="color: #0000FF;">)</span>
<span style="color: #004080;">integer</span> <span style="color: #000000;">left_max</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">heights</span><span style="color: #0000FF;">[</span><span style="color: #000000;">1</span><span style="color: #0000FF;">],</span>
<span style="color: #000000;">right_max</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">heights</span><span style="color: #0000FF;">[$]</span>
<span style="color: #004080;">sequence</span> <span style="color: #000000;">left_height</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">deep_copy</span><span style="color: #0000FF;">(</span><span style="color: #000000;">heights</span><span style="color: #0000FF;">),</span>
<span style="color: #000000;">right_height</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">deep_copy</span><span style="color: #0000FF;">(</span><span style="color: #000000;">heights</span><span style="color: #0000FF;">)</span>
<span style="color: #008080;">for</span> <span style="color: #000000;">i</span><span style="color: #0000FF;">=</span><span style="color: #000000;">2</span> <span style="color: #008080;">to</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">heights</span><span style="color: #0000FF;">)-</span><span style="color: #000000;">1</span> <span style="color: #008080;">do</span>
<span style="color: #000000;">left_max</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">max</span><span style="color: #0000FF;">(</span><span style="color: #000000;">heights</span><span style="color: #0000FF;">[</span><span style="color: #000000;">i</span><span style="color: #0000FF;">],</span><span style="color: #000000;">left_max</span><span style="color: #0000FF;">)</span>
<span style="color: #000000;">left_height</span><span style="color: #0000FF;">[</span><span style="color: #000000;">i</span><span style="color: #0000FF;">]</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">left_max</span>
<span style="color: #000000;">right_max</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">max</span><span style="color: #0000FF;">(</span><span style="color: #000000;">heights</span><span style="color: #0000FF;">[-</span><span style="color: #000000;">i</span><span style="color: #0000FF;">],</span><span style="color: #000000;">right_max</span><span style="color: #0000FF;">)</span>
<span style="color: #000000;">right_height</span><span style="color: #0000FF;">[-</span><span style="color: #000000;">i</span><span style="color: #0000FF;">]</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">right_max</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">for</span>
<span style="color: #004080;">sequence</span> <span style="color: #000000;">mins</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">sq_min</span><span style="color: #0000FF;">(</span><span style="color: #000000;">left_height</span><span style="color: #0000FF;">,</span><span style="color: #000000;">right_height</span><span style="color: #0000FF;">),</span>
<span style="color: #000000;">diffs</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">sq_sub</span><span style="color: #0000FF;">(</span><span style="color: #000000;">mins</span><span style="color: #0000FF;">,</span><span style="color: #000000;">heights</span><span style="color: #0000FF;">)</span>
<span style="color: #008080;">return</span> <span style="color: #7060A8;">sum</span><span style="color: #0000FF;">(</span><span style="color: #000000;">diffs</span><span style="color: #0000FF;">)</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">function</span>
<!--</syntaxhighlight>-->
(same output)
=== pretty print routine ===
<!--<syntaxhighlight lang="phix">(phixonline)-->
<span style="color: #008080;">with</span> <span style="color: #008080;">javascript_semantics</span>
<span style="color: #7060A8;">requires</span><span style="color: #0000FF;">(</span><span style="color: #008000;">"1.0.2"</span><span style="color: #0000FF;">)</span> <span style="color: #000080;font-style:italic;">-- (bugfix in p2js.js/$sidii(), 20/4/22)</span>
<span style="color: #008080;">procedure</span> <span style="color: #000000;">print_water</span><span style="color: #0000FF;">(</span><span style="color: #004080;">sequence</span> <span style="color: #000000;">heights</span><span style="color: #0000FF;">)</span>
<span style="color: #004080;">integer</span> <span style="color: #000000;">res</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">0</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">l</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">heights</span><span style="color: #0000FF;">)</span>
<span style="color: #004080;">sequence</span> <span style="color: #000000;">towers</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">repeat</span><span style="color: #0000FF;">(</span><span style="color: #7060A8;">repeat</span><span style="color: #0000FF;">(</span><span style="color: #008000;">' '</span><span style="color: #0000FF;">,</span><span style="color: #000000;">l</span><span style="color: #0000FF;">),</span><span style="color: #7060A8;">max</span><span style="color: #0000FF;">(</span><span style="color: #000000;">heights</span><span style="color: #0000FF;">))</span>
<span style="color: #008080;">for</span> <span style="color: #000000;">i</span><span style="color: #0000FF;">=</span><span style="color: #000000;">1</span> <span style="color: #008080;">to</span> <span style="color: #000000;">l</span> <span style="color: #008080;">do</span>
<span style="color: #008080;">for</span> <span style="color: #000000;">j</span><span style="color: #0000FF;">=</span><span style="color: #000000;">1</span> <span style="color: #008080;">to</span> <span style="color: #000000;">heights</span><span style="color: #0000FF;">[</span><span style="color: #000000;">i</span><span style="color: #0000FF;">]</span> <span style="color: #008080;">do</span>
<span style="color: #000000;">towers</span><span style="color: #0000FF;">[-</span><span style="color: #000000;">j</span><span style="color: #0000FF;">][</span><span style="color: #000000;">i</span><span style="color: #0000FF;">]</span> <span style="color: #0000FF;">=</span> <span style="color: #008000;">'#'</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">for</span>
<span style="color: #008080;">if</span> <span style="color: #000000;">i</span><span style="color: #0000FF;">></span><span style="color: #000000;">1</span> <span style="color: #008080;">and</span> <span style="color: #000000;">i</span><span style="color: #0000FF;"><</span><span style="color: #000000;">l</span> <span style="color: #008080;">then</span>
<span style="color: #004080;">integer</span> <span style="color: #000000;">lm</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">max</span><span style="color: #0000FF;">(</span><span style="color: #000000;">heights</span><span style="color: #0000FF;">[</span><span style="color: #000000;">1</span><span style="color: #0000FF;">..</span><span style="color: #000000;">i</span><span style="color: #0000FF;">-</span><span style="color: #000000;">1</span><span style="color: #0000FF;">]),</span>
<span style="color: #000000;">rm</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">max</span><span style="color: #0000FF;">(</span><span style="color: #000000;">heights</span><span style="color: #0000FF;">[</span><span style="color: #000000;">i</span><span style="color: #0000FF;">+</span><span style="color: #000000;">1</span><span style="color: #0000FF;">..$]),</span>
<span style="color: #000000;">m</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">min</span><span style="color: #0000FF;">(</span><span style="color: #000000;">lm</span><span style="color: #0000FF;">,</span><span style="color: #000000;">rm</span><span style="color: #0000FF;">)</span>
<span style="color: #008080;">for</span> <span style="color: #000000;">j</span><span style="color: #0000FF;">=</span><span style="color: #000000;">heights</span><span style="color: #0000FF;">[</span><span style="color: #000000;">i</span><span style="color: #0000FF;">]+</span><span style="color: #000000;">1</span> <span style="color: #008080;">to</span> <span style="color: #000000;">m</span> <span style="color: #008080;">do</span>
<span style="color: #000000;">towers</span><span style="color: #0000FF;">[-</span><span style="color: #000000;">j</span><span style="color: #0000FF;">][</span><span style="color: #000000;">i</span><span style="color: #0000FF;">]</span> <span style="color: #0000FF;">=</span> <span style="color: #008000;">'~'</span>
<span style="color: #000000;">res</span> <span style="color: #0000FF;">+=</span> <span style="color: #000000;">1</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">for</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">for</span>
<span style="color: #7060A8;">printf</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"%s\ncollected:%d\n"</span><span style="color: #0000FF;">,{</span><span style="color: #7060A8;">join</span><span style="color: #0000FF;">(</span><span style="color: #000000;">towers</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"\n"</span><span style="color: #0000FF;">),</span><span style="color: #000000;">res</span><span style="color: #0000FF;">})</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">procedure</span>
<span style="color: #000000;">print_water</span><span style="color: #0000FF;">({</span><span style="color: #000000;">5</span><span style="color: #0000FF;">,</span><span style="color: #000000;">3</span><span style="color: #0000FF;">,</span><span style="color: #000000;">7</span><span style="color: #0000FF;">,</span><span style="color: #000000;">2</span><span style="color: #0000FF;">,</span><span style="color: #000000;">6</span><span style="color: #0000FF;">,</span><span style="color: #000000;">4</span><span style="color: #0000FF;">,</span><span style="color: #000000;">5</span><span style="color: #0000FF;">,</span><span style="color: #000000;">9</span><span style="color: #0000FF;">,</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #000000;">2</span><span style="color: #0000FF;">})</span>
<!--</syntaxhighlight>-->
{{out}}
<pre>
#
#
#~~~~#
#~#~~#
#~#~#~##
#~#~####
###~####
########~#
##########
collected:14
</pre>
=={{header|Phixmonti}}==
{{trans|Phix}}
<syntaxhighlight lang="phixmonti">include ..\Utilitys.pmt
def collect_water
0 var res
len 1 - 2 swap 2 tolist
for
var i
1 i 1 - slice max >ps
len i - 1 + i swap slice max >ps
i get ps> ps> min swap -
0 max res + var res
endfor
drop
res
enddef
( ( 1 5 3 7 2 )
( 5 3 7 2 6 4 5 9 1 2 )
( 2 6 3 5 2 8 1 4 2 2 5 3 5 7 4 1 )
( 5 5 5 5 )
( 5 6 7 8 )
( 8 7 7 6 )
( 6 7 10 7 6 ) )
len for
endfor</syntaxhighlight>
{{out}}
[5, 3, 7,
[2, 6, 3, 5,
[5, 6, 7, 8] : 0
[8, 7, 7, 6] : 0
[6, 7, 10, 7, 6] : 0
=== Press any key to exit ===</pre>
=={{header|PicoLisp}}==
<syntaxhighlight lang="picolisp">(de water (Lst)
(sum
'((A)
(cnt
nT
(clip (mapcar '((B) (>= B A)) Lst)) ) )
(range 1 (apply max Lst)) ) )
(println
(mapcar
water
(quote
(1 5 3 7 2)
(5 3 7 2 6 4 5 9 1 2)
(2 6 3 5 2 8 1 4 2 2 5 3 5 7 4 1)
(5 5 5 5)
(5 6 7 8)
(8 7 7 6)
(6 7 10 7 6) ) ) )</syntaxhighlight>
{{out}}
<pre>(2 14 35 0 0 0 0)</pre>
Line 677 ⟶ 3,610:
Based on the algorithm explained at [http://stackoverflow.com/questions/24414700/amazon-water-collected-between-towers/32135773#32135773 Stack Overflow]:
<
N = len(tower)
highest_left = [0] + [max(tower[:n]) for n in range(1,N)]
Line 699 ⟶ 3,632:
[6, 7, 10, 7, 6]]
[water_collected(tower) for tower in towers]</
{{Out}}
<pre>
Line 745 ⟶ 3,678:
[2, 14, 35, 0, 0, 0, 0]</pre>
Or, expressed in terms of '''itertools.accumulate''', and showing diagrams:
<syntaxhighlight lang="python">'''Water collected between towers'''
from itertools import accumulate
from functools import reduce
from operator import add
# ---------------------- TOWER POOLS -----------------------
# towerPools :: [Int] -> [(Int, Int)]
def towerPools(towers):
'''Tower heights with water depths.
'''
def towerAndWater(level, tower):
return tower, level - tower
waterlevels = map(
min,
accumulate(towers, max),
reversed(list(
accumulate(reversed(towers), max)
)),
)
return list(map(towerAndWater, waterlevels, towers))
# ------------------------ DIAGRAMS ------------------------
# showTowers :: [(Int, Int)] -> String
def showTowers(xs):
'''Diagrammatic representation.
'''
upper = max(xs, key=fst)[0]
def row(xd):
return ' ' * (upper - add(*xd)) + (
snd(xd) * 'x' + '██' * fst(xd)
)
return unlines([
''.join(x) for x in zip(*map(row, xs))
])
# showLegend :: (Int, Int)] -> String
def showLegend(xs):
'''String display of tower heights and
total sum of trapped water units.
'''
towers, depths = zip(*xs)
return showList(towers) + (
' -> ' + str(sum(depths))
)
# -------------------------- TEST --------------------------
# main :: IO ()
def main():
'''Water collected in various flooded bar charts.'''
def diagram(xs):
return showTowers(xs) + '\n\n' + (
showLegend(xs) + '\n\n'
)
print(unlines(
map(compose(diagram, towerPools), [
[1, 5, 3, 7, 2],
[5, 3, 7, 2, 6, 4, 5, 9, 1, 2],
[2, 6, 3, 5, 2, 8, 1, 4, 2, 2, 5, 3, 5, 7, 4, 1],
[5, 5, 5, 5],
[5, 6, 7, 8],
[8, 7, 7, 6],
[6, 7, 10, 7, 6]
])
))
# ------------------------ GENERIC -------------------------
# compose :: ((a -> a), ...) -> (a -> a)
def compose(*fs):
'''Composition, from right to left,
of a series of functions.
'''
def go(f, g):
return lambda x: f(g(x))
return reduce(go, fs, lambda x: x)
# fst :: (a, b) -> a
def fst(tpl):
'''First member of a pair.'''
return tpl[0]
# showList :: [a] -> String
def showList(xs):
'''Stringification of a list.'''
return '[' + ','.join(str(x) for x in xs) + ']'
# snd :: (a, b) -> b
def snd(tpl):
'''Second member of a pair.'''
return tpl[1]
# unlines :: [String] -> String
def unlines(xs):
'''A single string formed by the intercalation
of a list of strings with the newline character.
'''
return '\n'.join(xs)
# MAIN ---
if __name__ == '__main__':
main()
</syntaxhighlight>
{{Out}}
<pre> █
█
█x█
█x█
███
████
█████
█████
[1,5,3,7,2] -> 2
█
█
█xxxx█
█x█xx█
█x█x█x██
█x█x████
███x████
████████x█
██████████
██████████
[5,3,7,2,6,4,5,9,1,2] -> 14
█
█xxxxxxx█
█xxx█xxxxxxx█
█x█x█xxxx█x██
█x█x█x█xx█x███
███x█x█xx█████
██████x████████
████████████████
████████████████
[2,6,3,5,2,8,1,4,2,2,5,3,5,7,4,1] -> 35
████
████
████
████
████
████
████
████
████
████
[5,5,5,5] -> 0
█
██
███
████
████
████
████
████
████
████
████
████
████
[5,6,7,8] -> 0
█
███
████
████
████
████
████
████
████
████
████
████
████
████
[8,7,7,6] -> 0
█
█
█
███
█████
█████
█████
█████
█████
█████
█████
█████
█████
█████
█████
█████
[6,7,10,7,6] -> 0</pre>
=={{header|Quackery}}==
<syntaxhighlight lang="Quackery"> [ $ "turtleduck.qky" loadfile ] now!
[ dup 0 = iff drop done
dup 2 times
[ 20 * 1 walk
1 4 turn
20 1 walk
1 4 turn ] ] is bar ( [ --> )
[ tuck size unrot
-1 4 turn
witheach
[ dup
' [ 158 151 147 ]
dup colour
fill bar
dup 20 * 1 fly
dip
[ behead
' [ 162 197 208 ]
dup colour
fill bar ]
-20 * 1 fly
1 4 turn
20 1 fly
-1 4 turn ]
drop
1 4 turn
-20 * 1 fly ] is chart ( [ [ --> )
[ [] 0 rot witheach
[ max dup dip join ]
drop ] is rightmax ( [ --> [ )
[ reverse
rightmax
reverse ] is leftmax ( [ --> [ )
[ [] unrot
witheach
[ over i^ peek
min swap dip join ]
drop ] is mins ( [ --> [ )
[ [] unrot
witheach
[ over i^ peek
- swap dip join ]
drop ] is diffs ( [ --> [ )
[ 0 swap witheach + ] is sum ( [ --> n )
[ dup 2dup rightmax
swap leftmax
mins diffs chart ] is task1 ( [ --> )
[ dup dup rightmax
swap leftmax
mins diffs sum ] is task2 ( [ --> )
turtle
10 frames
-540 1 fly
' [ [ 1 5 3 7 2 ]
[ 5 3 7 2 6 4 5 9 1 2 ]
[ 2 6 3 5 2 8 1 4 2 2 5 3 5 7 4 1 ]
[ 5 5 5 5 ]
[ 5 6 7 8 ]
[ 8 7 7 6 ]
[ 6 7 10 7 6 ] ]
dup
witheach
[ dup size swap
task1
1+ 20 * 1 fly ]
witheach
[ task2 echo sp ]
1 frames</syntaxhighlight>
{{out}}
I see from the discussion page that drawing the towers wasn't part of the task. Here they are anyway.
"What is the use of a book," thought Alice, "without pictures or conversations?"
[[File:Quackery - Water collected between towers.png|thumb|center]]
<pre>2 14 35 0 0 0 0</pre>
=={{header|Racket}}==
<syntaxhighlight lang="racket">#lang racket/base
(require racket/match)
(define (water-collected-between-towers towers)
(define (build-tallest-left/rev-list t mx/l rv)
(match t
[(list) rv]
[(cons a d)
(define new-mx/l (max a mx/l))
(build-tallest-left/rev-list d new-mx/l (cons mx/l rv))]))
(define (collect-from-right t tallest/l mx/r rv)
(match t
[(list) rv]
[(cons a d)
(define new-mx/r (max a mx/r))
(define new-rv (+ rv (max (- (min new-mx/r (car tallest/l)) a) 0)))
(collect-from-right d (cdr tallest/l) new-mx/r new-rv)]))
(define reversed-left-list (build-tallest-left/rev-list towers 0 null))
(collect-from-right (reverse towers) reversed-left-list 0 0))
(module+ test
(require rackunit)
(check-equal?
(let ((towerss
'[[1 5 3 7 2]
[5 3 7 2 6 4 5 9 1 2]
[2 6 3 5 2 8 1 4 2 2 5 3 5 7 4 1]
[5 5 5 5]
[5 6 7 8]
[8 7 7 6]
[6 7 10 7 6]]))
(map water-collected-between-towers towerss))
(list 2 14 35 0 0 0 0)))</syntaxhighlight>
When run produces no output -- meaning that the tests have run successfully.
=={{header|Raku}}==
(formerly Perl 6)
{{Trans|Haskell}}
<syntaxhighlight lang="raku" line>sub max_l ( @a ) { [\max] @a }
sub max_r ( @a ) { ([\max] @a.reverse).reverse }
sub water_collected ( @towers ) {
return 0 if @towers <= 2;
my @levels = max_l(@towers) »min« max_r(@towers);
return ( @levels »-« @towers ).grep( * > 0 ).sum;
}
say map &water_collected,
[ 1, 5, 3, 7, 2 ],
[ 5, 3, 7, 2, 6, 4, 5, 9, 1, 2 ],
[ 2, 6, 3, 5, 2, 8, 1, 4, 2, 2, 5, 3, 5, 7, 4, 1 ],
[ 5, 5, 5, 5 ],
[ 5, 6, 7, 8 ],
[ 8, 7, 7, 6 ],
[ 6, 7, 10, 7, 6 ],
;</syntaxhighlight>
{{Out}}
<pre>(2 14 35 0 0 0 0)</pre>
=={{header|REXX}}==
===version 1===
<
Call bars '1 5 3 7 2'
Call bars '5 3 7 2 6 4 5 9 1 2'
Line 813 ⟶ 4,133:
Say ol
End
Return</
{{out}}
<pre>1 5 3 7 2 -> 2
Line 878 ⟶ 4,198:
x x x x x</pre>
===version 2, simple numeric list output===
<
call tower 1 5 3 7 2
call tower 5 3 7 2 6 4 5 9 1 2
call tower 2 6 3 5 2 8 1 4 2 2 5 3 5 7 4 1
call tower 5 5 5 5
call tower 5 6 7 8
call tower 8 7 7 6
call tower 6 7 10 7 6
exit /*stick a fork in it, we're all done. */
/*──────────────────────────────────────────────────────────────────────────────────────*/
tower: procedure; arg y; #=words(y); t.=0; L.=0 /*the T. array holds the tower heights.*/
do j=1 for #; t.j= word(y, j)
_= j-1; L.j= max(t._, L._)
end /*j*/
R.=0
do b=# by -1 for #; _= b+1;
end /*b*/
w.=0 /*rainwater collected.*/
do f=1 for #; if t.f>=L.f | t.f>=R.f then iterate /*rain between towers?*/
w.f= min(L.f, R.f) - t.f;
end /*f*/
say right(w.00, 9) 'units of rainwater collected for: ' y
return</
<pre>
2 units of rainwater collected for: 1 5 3 7 2
Line 913 ⟶ 4,233:
</pre>
===version 3, with ASCII art===
This REXX version shows a scale (showing the number of floors in the building) and a representation of the towers and water collected.
It tries to protect the aspect ratio by showing the buildings as in this task's preamble.
<syntaxhighlight lang="rexx">/*REXX program calculates and displays the amount of rainwater collected between towers.*/
call tower 1 5 3 7 2
call tower 5 3 7 2 6 4 5 9 1 2
Line 925 ⟶ 4,247:
exit /*stick a fork in it, we're all done. */
/*──────────────────────────────────────────────────────────────────────────────────────*/
tower: procedure; arg y; #= words(y); t.=0; L.=0
do j=1 for #; t.j=word(y,j); _=j-1 /*construct the towers; max height. */
L.j=max(t._, L._); t.0=max(t.0, t.j) /*left-most tallest tower; build scale.*/
end /*j*/
R.=0
do b=# by -1 for #;
end /*b*/
w.=0 /*rainwater collected.*/
do f=1 for #; if t.f>=L.f | t.f>=R.f then iterate /*rain between towers?*/
w.f= min(L.f, R.f) - t.f;
end /*f*/
if w.00==0 then w.00= 'no'
ratio= 2 /*used to maintain a good aspect ratio.*/
p.= /*P. stores plot versions of towers. */
do c=0 to #; cc= c *
do h=1 for t.c+w.c;
if c==0 then p.h= overlay(right(h, 9) , p.h, 1 )
else p.h= overlay(copies(glyph
end /*h*/
end /*c*/
p.1= overlay(w.00 'units of rainwater collected', p.1, 15*ratio+#)
do z=t.0 by -1 to 0; say p.z /*display various tower floors & water.*/
end /*z*/
return</
<pre>
7
6
5
4
3
2
1
9
8
7
6
5 ██≈≈██≈≈██≈≈████
4 ██≈≈██≈≈████████
3 ██████≈≈████████
2 ████████████████≈≈██
1
8
7 ██≈≈≈≈≈≈≈≈≈≈≈≈≈≈██
6 ██≈≈≈≈≈≈██≈≈≈≈≈≈≈≈≈≈≈≈≈≈██
5 ██≈≈██≈≈██≈≈≈≈≈≈≈≈██≈≈████
4 ██≈≈██≈≈██≈≈██≈≈≈≈██≈≈██████
3 ██████≈≈██≈≈██≈≈≈≈██████████
2 ████████████≈≈████████████████
1
5
4
3
2
1
8
7
6
5
4
3
2
1
8
7
6
5
4
3
2
1
10
9
8
7
6
5
4
3
2
1
</pre>
=={{header|RPL}}==
{{trans|Python}}
{{works with|HP|49/50}}
« DUPDUP SIZE 1 - NDUPN →LIST
DUP 1 « 1 NSUB SUB 0 + « MAX » STREAM » DOSUBS 0 SWAP + <span style="color:grey">@ the seq of max heights to the left of each tower</span>
SWAP 1 « NSUB 1 + OVER SIZE SUB 0 + « MAX » STREAM » DOSUBS 0 + <span style="color:grey">@ the seq of max heights to the right of each tower</span>
MIN SWAP -
1 « 0 MAX » DOLIST ∑LIST
» '<span style="color:blue">WATER</span>' STO
« { {1 5 3 7 2}
{5 3 7 2 6 4 5 9 1 2}
{2 6 3 5 2 8 1 4 2 2 5 3 5 7 4 1}
{5 5 5 5}
{5 6 7 8}
{8 7 7 6}
{6 7 10 7 6} }
1 « <span style="color:blue">WATER</span> » DOLIST
» '<span style="color:blue">TASK</span>' STO
{{out}}
<pre>
1: { 2 14 35 0 0 0 0 }
</pre>
=={{header|Ruby}}==
<
def a(array)
n=array.length
Line 1,050 ⟶ 4,397:
a([ 8, 7, 7, 6 ])
a([ 6, 7, 10, 7, 6 ])
return</
'''output'''
<pre>
Line 1,061 ⟶ 4,408:
</pre>
=={{header|
<syntaxhighlight lang="rust">
use std::cmp::min;
fn getfill(pattern: &[usize]) -> usize {
let mut total = 0;
for (idx, val) in pattern.iter().enumerate() {
let l_peak = pattern[..idx].iter().max();
let r_peak = pattern[idx + 1..].iter().max();
if l_peak.is_some() && r_peak.is_some() {
let peak = min(l_peak.unwrap(), r_peak.unwrap());
if peak > val {
total += peak - val;
}
}
}
total
}
fn main() {
let patterns = vec![
vec![1, 5, 3, 7, 2],
vec![5, 3, 7, 2, 6, 4, 5, 9, 1, 2],
vec![2, 6, 3, 5, 2, 8, 1, 4, 2, 2, 5, 3, 5, 7, 4, 1],
vec![5, 5, 5, 5],
vec![5, 6, 7, 8],
vec![8, 7, 7, 6],
vec![6, 7, 10, 7, 6],
];
for pattern in patterns {
println!("pattern: {:?}, fill: {}", &pattern, getfill(&pattern));
}
}
</syntaxhighlight>
'''output'''
<pre>
pattern: [1, 5, 3, 7, 2], fill: 2
pattern: [5, 3, 7, 2, 6, 4, 5, 9, 1, 2], fill: 14
pattern: [2, 6, 3, 5, 2, 8, 1, 4, 2, 2, 5, 3, 5, 7, 4, 1], fill: 35
pattern: [5, 5, 5, 5], fill: 0
pattern: [5, 6, 7, 8], fill: 0
pattern: [8, 7, 7, 6], fill: 0
pattern: [6, 7, 10, 7, 6], fill: 0
</pre>
=={{header|Scala}}==
===No sweat.===
{{Out}}See it yourself by running in your browser either by [https://scalafiddle.io/sf/jx29Ace/0 ScalaFiddle (ES aka JavaScript, non JVM)] or [https://scastie.scala-lang.org/5nXQHfR0T0iauHNWSTRntg Scastie (remote JVM)].
{{libheader|Scala Concise}}
{{libheader|Scala Parallel Programming}}
{{libheader|Scala Time complexity O(n)}}
{{libheader|ScalaFiddle qualified}}
{{libheader|Scastie qualified}}
{{works with|Scala|2.13}}
<syntaxhighlight lang="scala">import scala.collection.parallel.CollectionConverters.VectorIsParallelizable
// Program to find maximum amount of water
// that can be trapped within given set of bars.
object TrappedWater extends App {
private val barLines = List(
Vector(1, 5, 3, 7, 2),
Vector(5, 3, 7, 2, 6, 4, 5, 9, 1, 2),
Vector(2, 6, 3, 5, 2, 8, 1, 4, 2, 2, 5, 3, 5, 7, 4, 1),
Vector(5, 5, 5, 5),
Vector(5, 6, 7, 8),
Vector(8, 7, 7, 6),
Vector(6, 7, 10, 7, 6)).zipWithIndex
// Method for maximum amount of water
private def sqBoxWater(barHeights: Vector[Int]): Int = {
def maxOfLeft = barHeights.par.scanLeft(0)(math.max).tail
def maxOfRight = barHeights.par.scanRight(0)(math.max).init
def waterlevels = maxOfLeft.zip(maxOfRight)
.map { case (maxL, maxR) => math.min(maxL, maxR) }
waterlevels.zip(barHeights).map { case (level, towerHeight) => level - towerHeight }.sum
}
barLines.foreach(barSet =>
println(s"Block ${barSet._2 + 1} could hold max. ${sqBoxWater(barSet._1)} units."))
}</syntaxhighlight>
=={{header|Scheme}}==
<syntaxhighlight lang="scheme">(import (scheme base)
(scheme write))
Line 1,097 ⟶ 4,527:
(5 6 7 8)
(8 7 7 6)
(6 7 10 7 6)))</syntaxhighlight>
{{out}}
<pre>(1 5 3 7 2) -> 2
(5 3 7 2 6 4 5 9 1 2) -> 14
(2 6 3 5 2 8 1 4 2 2 5 3 5 7 4 1) -> 35
Line 1,112 ⟶ 4,539:
(1) -> 0
() -> 0
(1 2) -> 0</pre>
=={{header|Sidef}}==
<
gather { a.each {|e| take(m = max(m, e)) } }
}
Line 1,137 ⟶ 4,563:
[ 8, 7, 7, 6 ],
[ 6, 7, 10, 7, 6 ],
].map { water_collected(_) }.say</
{{out}}
<pre>
[2, 14, 35, 0, 0, 0, 0]
</pre>
=={{header|Swift}}==
<syntaxhighlight lang="swift">// Based on this answer from Stack Overflow:
// https://stackoverflow.com/a/42821623
func waterCollected(_ heights: [Int]) -> Int {
guard heights.count > 0 else {
return 0
}
var water = 0
var left = 0, right = heights.count - 1
var maxLeft = heights[left], maxRight = heights[right]
while left < right {
if heights[left] <= heights[right] {
maxLeft = max(heights[left], maxLeft)
water += maxLeft - heights[left]
left += 1
} else {
maxRight = max(heights[right], maxRight)
water += maxRight - heights[right]
right -= 1
}
}
return water
}
for heights in [[1, 5, 3, 7, 2],
[5, 3, 7, 2, 6, 4, 5, 9, 1, 2],
[2, 6, 3, 5, 2, 8, 1, 4, 2, 2, 5, 3, 5, 7, 4, 1],
[5, 5, 5, 5],
[5, 6, 7, 8],
[8, 7, 7, 6],
[6, 7, 10, 7, 6]] {
print("water collected = \(waterCollected(heights))")
}</syntaxhighlight>
{{out}}
<pre>
water collected = 2
water collected = 14
water collected = 35
water collected = 0
water collected = 0
water collected = 0
water collected = 0
</pre>
=={{header|Tailspin}}==
<syntaxhighlight lang="tailspin">
templates histogramWater
$ -> \( @: 0"1";
[$... -> ($)"1"-> { leftMax: $ -> #, value: ($)"1" } ] !
when <$@..> do @: $; $ !
otherwise $@ !
\) -> \( @: { rightMax: 0"1", sum: 0"1" };
$(last..1:-1)... -> #
$@.sum !
when <{ value: <$@.rightMax..> }> do @.rightMax: $.value;
when <{ value: <$.leftMax..> }> do !VOID
when <{ leftMax: <..$@.rightMax>}> do @.sum: $@.sum + $.leftMax - $.value;
otherwise @.sum: $@.sum + $@.rightMax - $.value;
\) !
end histogramWater
[[1, 5, 3, 7, 2],
[5, 3, 7, 2, 6, 4, 5, 9, 1, 2],
[2, 6, 3, 5, 2, 8, 1, 4, 2, 2, 5, 3, 5, 7, 4, 1],
[5, 5, 5, 5],
[5, 6, 7, 8],
[8, 7, 7, 6],
[6, 7, 10, 7, 6]]... -> '$ -> histogramWater; water in $;$#10;' -> !OUT::write
</syntaxhighlight>
{{out}}
<pre>
2"1" water in [1, 5, 3, 7, 2]
14"1" water in [5, 3, 7, 2, 6, 4, 5, 9, 1, 2]
35"1" water in [2, 6, 3, 5, 2, 8, 1, 4, 2, 2, 5, 3, 5, 7, 4, 1]
0"1" water in [5, 5, 5, 5]
0"1" water in [5, 6, 7, 8]
0"1" water in [8, 7, 7, 6]
0"1" water in [6, 7, 10, 7, 6]
</pre>
=={{header|Tcl}}==
Tcl makes for a surprisingly short and readable implementation, next to some of the more functional-oriented languages.
<
proc flood {ground} {
Line 1,179 ⟶ 4,689:
} {
puts [flood $p]:\t$p
}</
{{out}}
Line 1,191 ⟶ 4,701:
0: 6 7 10 7 6</pre>
=={{header|
{{trans|Kotlin}}
{{libheader|Wren-math}}
{{libheader|Wren-fmt}}
<syntaxhighlight lang="wren">import "./math" for Math, Nums
import "./fmt" for Fmt
var waterCollected = Fn.new { |tower|
var n = tower.count
var highLeft = [0] + (1...n).map { |i| Nums.max(tower[0...i]) }.toList
var highRight = (1...n).map { |i| Nums.max(tower[i...n]) }.toList + [0]
var t = (0...n).map { |i| Math.max(Math.min(highLeft[i], highRight[i]) - tower[i], 0) }
return Nums.sum(t)
}
var towers = [
[1, 5, 3, 7, 2],
[5, 3, 7, 2, 6, 4, 5, 9, 1, 2],
[2, 6, 3, 5, 2, 8, 1, 4, 2, 2, 5, 3, 5, 7, 4, 1],
[5, 5, 5, 5],
[5, 6, 7, 8],
[8, 7, 7, 6],
[6, 7, 10, 7, 6]
]
for (tower in towers) Fmt.print("$2d from $n", waterCollected.call(tower), tower)</syntaxhighlight>
{{out}}
<pre>
2 from [1, 5, 3, 7, 2]
14 from [5, 3, 7, 2, 6, 4, 5, 9, 1, 2]
35 from [2, 6, 3, 5, 2, 8, 1, 4, 2, 2, 5, 3, 5, 7, 4, 1]
0 from [5, 5, 5, 5]
0 from [5, 6, 7, 8]
0 from [8, 7, 7,
0 from [6, 7, 10, 7,
</pre>
=={{header|XPL0}}==
<syntaxhighlight lang="xpl0">func WaterCollected(Array, Width); \Return amount of water collected
int Array, Width, Height, I, Row, Col, Left, Right, Water;
[Water:= 0; Height:= 0;
for I:= 0 to Width-1 do \find max height
if Array(I) > Height then Height:= Array(I);
for Row:= 2 to Height do
for Col:= 1 to Width-2 do \(zero-based)
if Row > Array(Col) then \empty location
[Left:= false; Right:= false; \check for barriers
for I:= 0 to Width-1 do
if Array(I) >= Row then \have barrier
[if I < Col then Left:= true;
if I > Col then Right:= true;
];
if Left & Right then Water:= Water+1;
];
return Water;
];
int Towers, I;
[Towers:=[[1, 5, 3, 7, 2],
[5, 3, 7, 2, 6, 4, 5, 9, 1, 2],
[2, 6, 3, 5, 2, 8, 1, 4, 2, 2, 5, 3, 5, 7, 4, 1],
[5, 5, 5, 5],
[5, 6, 7, 8],
[6, 7, 10, 7, 6],
[0]]; \for determining sub-array lengths
for I:= 0 to 7-1 do
[IntOut( 0, WaterCollected(Towers(I), (Towers(I+1)-Towers(I))/4) );
ChOut(0, ^ );
];
]</syntaxhighlight>
{{out}}
<pre>
2 14 35 0 0 0 0
</pre>
=={{header|zkl}}==
{{trans|Haskell}}
<
// compile max wall heights from left to right and right to left
// then each pair is left/right wall of that cell.
Line 1,339 ⟶ 4,793:
xs.reduce('wrap(s,x,a){ s=f(s,x); a.append(s); s },i,ss:=List());
ss
} // scanl((1,5,3,7,2),max,0) --> (1,5,5,7,7)</
<
T(2, 6, 3, 5, 2, 8, 1, 4, 2, 2, 5, 3, 5, 7, 4, 1),
T(5, 5, 5, 5), T(5, 6, 7, 8),T(8, 7, 7, 6),
T(6, 7, 10, 7, 6) )
.pump(List, waterCollected).println();</
{{out}}
<pre>
| |||