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Next highest int from digits: Difference between revisions
→{{header|Nim}}
Line 1,265:
Permutations unique: OK = true
Permutation count: Actual = 10, Expected = 10, OK = true</pre>
=={{header|Nim}}==
Using the scanning algorithm.
<lang Nim>import algorithm
type Digit = range[0..9]
func digits(n: Natural): seq[Digit] =
## Return the list of digits of "n" in reverse order.
if n == 0: return @[Digit 0]
var n = n
while n != 0:
result.add n mod 10
n = n div 10
func nextHighest(n: Natural): Natural =
## Find the next highest integer of "n".
## If none is found, "n" is returned.
var d = digits(n) # Warning: in reverse order.
var m = d[0]
for i in 1..d.high:
if d[i] < m:
# Find the digit greater then d[i] and closest to it.
var delta = m - d[i] + 1
var best: int
for j in 0..<i:
let diff = d[j] - d[i]
if diff > 0 and diff < delta:
# Greater and closest.
delta = diff
best = j
# Exchange digits.
swap d[i], d[best]
# Sort previous digits.
d[0..<i] = sorted(d.toOpenArray(0, i - 1), Descending)
break
else:
m = d[i]
# Compute the value from the digits.
for val in reversed(d):
result = 10 * result + val
when isMainModule:
for n in [0, 9, 12, 21, 12453, 738440, 45072010, 95322020]:
echo n, " → ", nextHighest(n)</lang>
{{out}}
<pre>0 → 0
9 → 9
12 → 21
21 → 21
12453 → 12534
738440 → 740348
45072010 → 45072100
95322020 → 95322200</pre>
=={{header|Perl}}==
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