<?php
$arr = [ 1,2,3,4 ];
$expected = [
'1-2-3-4',
'2-1-3-4',
'3-1-2-4',
'1-3-2-4',
'2-3-1-4',
'3-2-1-4',
'4-2-1-3',
'2-4-1-3',
'1-4-2-3',
'4-1-2-3',
'2-1-4-3',
'1-2-4-3',
'1-3-4-2',
'3-1-4-2',
'4-1-3-2',
'1-4-3-2',
'3-4-1-2',
'4-3-1-2',
'4-3-2-1',
'3-4-2-1',
'2-4-3-1',
'4-2-3-1',
'3-2-4-1',
'2-3-4-1',
];
function mixture( $size, array &$collection ) {
$permutations = [];
$offset = $size - 1;
if ( 1 === $size ) {
$permutations[] = implode( '-', $collection );
return $permutations;
}
for ( $i = 0; $i < $offset; $i++ ) {
$permutations = array_merge( $permutations, mixture( $offset, $collection ) );
$j = ( 0 == $size % 2 ) ? $i : 0;
$tmp_el = $collection[ $offset ];
$collection[ $offset ] = $collection[ $j ];
$collection[ $j ] = $tmp_el;
}
$permutations = array_merge( $permutations, mixture( $offset, $collection ) );
return $permutations;
}
print_r($permutations = mixture( count($arr), $arr ));
if ($expected == $permutations) {
echo 'PASS'.PHP_EOL;
} else {
echo 'FAIL'.PHP_EOL;
echo 'missing: '.PHP_EOL;
print_r(array_diff($expected, array_unique($permutations)));
}
- Output for 7.0.0 - 7.0.20, 7.1.0 - 7.1.33, 7.2.0 - 7.2.33, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.29, 8.2.0 - 8.2.20, 8.3.0 - 8.3.8
- Array
(
[0] => 1-2-3-4
[1] => 2-1-3-4
[2] => 3-1-2-4
[3] => 1-3-2-4
[4] => 2-3-1-4
[5] => 3-2-1-4
[6] => 4-2-1-3
[7] => 2-4-1-3
[8] => 1-4-2-3
[9] => 4-1-2-3
[10] => 2-1-4-3
[11] => 1-2-4-3
[12] => 1-3-4-2
[13] => 3-1-4-2
[14] => 4-1-3-2
[15] => 1-4-3-2
[16] => 3-4-1-2
[17] => 4-3-1-2
[18] => 4-3-2-1
[19] => 3-4-2-1
[20] => 2-4-3-1
[21] => 4-2-3-1
[22] => 3-2-4-1
[23] => 2-3-4-1
)
PASS
preferences:
176.95 ms | 404 KiB | 222 Q