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run code in 150+ php & hhvm versions
Bugs & Features
<?php function permuteUnique($items, $perms = [], &$return = []) { if (empty($items)) { $return[] = $perms; } else { sort($items); $prev = false; for ($i = count($items) - 1; $i >= 0; --$i) { $newitems = $items; $tmp = array_splice($newitems, $i, 1)[0]; if ($tmp != $prev) { $prev = $tmp; $newperms = $perms; array_unshift($newperms, $tmp); permuteUnique($newitems, $newperms, $return); } } return $return; } } $permutations = permuteUnique(["x1", "x2", "x3"]); var_dump($permutations);
Output for 5.4.0 - 5.6.28, hhvm-3.10.0 - 3.13.2, 7.0.0 - 7.1.0
array(6) { [0]=> array(3) { [0]=> string(2) "x1" [1]=> string(2) "x2" [2]=> string(2) "x3" } [1]=> array(3) { [0]=> string(2) "x2" [1]=> string(2) "x1" [2]=> string(2) "x3" } [2]=> array(3) { [0]=> string(2) "x1" [1]=> string(2) "x3" [2]=> string(2) "x2" } [3]=> array(3) { [0]=> string(2) "x3" [1]=> string(2) "x1" [2]=> string(2) "x2" } [4]=> array(3) { [0]=> string(2) "x2" [1]=> string(2) "x3" [2]=> string(2) "x1" } [5]=> array(3) { [0]=> string(2) "x3" [1]=> string(2) "x2" [2]=> string(2) "x1" } }
Output for 4.4.2 - 4.4.9, 5.1.0 - 5.3.29
Parse error: syntax error, unexpected '[' in /in/RLS36 on line 2
Process exited with code 255.
Output for 4.3.0 - 4.3.1, 4.3.5 - 4.4.1, 5.0.0 - 5.0.5
Parse error: parse error, unexpected '[' in /in/RLS36 on line 2
Process exited with code 255.
Output for 4.3.2 - 4.3.4
Parse error: parse error in /in/RLS36 on line 2
Process exited with code 255.