Multiplication tables
You are encouraged to solve this task according to the task description, using any language you may know.
Produce a formatted 12×12 multiplication table of the kind memorised by rote when in primary school.
Only print the top half triangle of products.
ALGOL 68
<lang Algol68>main:(
INT max = 12; STRING empty cell = " "; FORMAT fmt = $zz-d$;
print(" x");
FOR col TO max DO printf((fmt, col)) OD;
print (new line);
FOR row TO max DO printf((fmt,row)); FOR col TO row-1 DO print(empty cell) OD; [row:max]INT product; FOR col FROM row TO max DO product[col]:=row*col OD; printf((fmt, product, $l$)) OD
)</lang> Output:
x 1 2 3 4 5 6 7 8 9 10 11 12 1 1 2 3 4 5 6 7 8 9 10 11 12 2 4 6 8 10 12 14 16 18 20 22 24 3 9 12 15 18 21 24 27 30 33 36 4 16 20 24 28 32 36 40 44 48 5 25 30 35 40 45 50 55 60 6 36 42 48 54 60 66 72 7 49 56 63 70 77 84 8 64 72 80 88 96 9 81 90 99 108 10 100 110 120 11 121 132 12 144
C++
This is a slightly more-generalized version that takes any minimum and maximum table value, and formats the table columns.
<lang cpp>#include <iostream>
- include <iomanip>
- include <cmath>
- define MAX(a, b) (a > b ? a : b)
- define ABS(x) (x > 0 ? x : (0 - x) )
size_t get_table_column_width(const int min, const int max) {
unsigned int abs_max = 0; abs_max = MAX(abs_max, ABS(max*max)); abs_max = MAX(abs_max, ABS(max*min)); abs_max = MAX(abs_max, ABS(min*min));
// abs_max is the largest absolute value we might see. // If we take the log10 and add one, we get the string width // of the largest possible absolute value. // Add one for a little whitespace guarantee. size_t colwidth = (1 + log10(abs_max)) + 1;
bool has_negative_result = false;
// If both are less than 0, then all results will be positive
if(!(min < 0) && (max < 0))
{
// If only one of them is less than 0, then some will
// be negative.
if((min < 0) || (max < 0 ))
has_negative_result = true;
}
// If some values may be negative, then we need to add some space
// for a sign indicator (-)
if(has_negative_result)
colwidth += 1;
return colwidth;
}
void print_table_header(const int min, const int max) {
size_t colwidth = get_table_column_width(min, max);
// table corner
std::cout << std::setw(colwidth) << " ";
for(int col = min; col <= max; ++col)
{
std::cout << std::setw(colwidth) << col;
}
// End header with a newline and blank line. std::cout << std::endl << std::endl;
}
void print_table_row(const int num, const int min, const int max) {
size_t colwidth = get_table_column_width(min, max);
// Header column std::cout << std::setw(colwidth) << num;
// Spacing to ensure only the top half is printed
for(int multiplicand = min; multiplicand < num; ++multiplicand)
{
std::cout << std::setw(colwidth) << " ";
}
// Remaining multiplicands for the row.
for(int multiplicand = num; multiplicand <= max; ++multiplicand)
{
std::cout << std::setw(colwidth) << num * multiplicand;
}
// End row with a newline and blank line. std::cout << std::endl << std::endl;
}
void print_table(const int min, const int max) {
// Header row print_table_header(min, max);
// Table body
for(int row = min; row <= max; ++row)
{
print_table_row(row, min, max);
}
}
int main() {
print_table(1, 12); return 0;
} </lang>
Output:
1 2 3 4 5 6 7 8 9 10 11 12 1 1 2 3 4 5 6 7 8 9 10 11 12 2 4 6 8 10 12 14 16 18 20 22 24 3 9 12 15 18 21 24 27 30 33 36 4 16 20 24 28 32 36 40 44 48 5 25 30 35 40 45 50 55 60 6 36 42 48 54 60 66 72 7 49 56 63 70 77 84 8 64 72 80 88 96 9 81 90 99 108 10 100 110 120 11 121 132 12 144
Haskell
<lang haskell>import Control.Monad import Text.Printf
main = do
putStrLn $ " x" ++ concatMap fmt [1..12]
zipWithM_ f [1..12] $ iterate (" " ++) ""
where f n s = putStrLn $ fmt n ++ s ++ concatMap (fmt . (*n)) [n..12]
fmt n = printf "%4d" (n :: Int)</lang>
Python
<lang python>>>> for row in range(13): print(" ".join("%3s" % ("x" if row==col==0 else row if row and col==0 else col if row==0 else "" if row>col else row*col) for col in range(13)))
x 1 2 3 4 5 6 7 8 9 10 11 12 1 1 2 3 4 5 6 7 8 9 10 11 12 2 4 6 8 10 12 14 16 18 20 22 24 3 9 12 15 18 21 24 27 30 33 36 4 16 20 24 28 32 36 40 44 48 5 25 30 35 40 45 50 55 60 6 36 42 48 54 60 66 72 7 49 56 63 70 77 84 8 64 72 80 88 96 9 81 90 99 108 10 100 110 120 11 121 132 12 144
>>> </lang>
Tcl
<lang tcl>puts " x\u2502 1 2 3 4 5 6 7 8 9 10 11 12" puts \u0020\u2500\u2500\u253c[string repeat \u2500 48] for {set i 1} {$i <= 12} {incr i} {
puts -nonewline [format "%3d" $i]\u2502[string repeat " " [expr {$i*4-4}]]
for {set j 1} {$j <= 12} {incr j} {
if {$j >= $i} { puts -nonewline [format "%4d" [expr {$i*$j}]] }
} puts ""
}</lang> Output:
x│ 1 2 3 4 5 6 7 8 9 10 11 12 ──┼──────────────────────────────────────────────── 1│ 1 2 3 4 5 6 7 8 9 10 11 12 2│ 4 6 8 10 12 14 16 18 20 22 24 3│ 9 12 15 18 21 24 27 30 33 36 4│ 16 20 24 28 32 36 40 44 48 5│ 25 30 35 40 45 50 55 60 6│ 36 42 48 54 60 66 72 7│ 49 56 63 70 77 84 8│ 64 72 80 88 96 9│ 81 90 99 108 10│ 100 110 120 11│ 121 132 12│ 144