function pc_permute($items, $perms = array()) {
if (empty($items)) {
echo join(‘ ‘, $perms) . “
“;
} else {
for ($i = count($items) - 1; $i >= 0; –$i) {
$newitems = $items;
$newperms = $perms;
list($foo) = array_splice($newitems, $i, 1);
array_unshift($newperms, $foo);
pc_permute($newitems, $newperms);
}
}
}
$arr = array('peter', 'paul', 'mary');pc_permute($arr);要么
function pc_next_permutation($p, $size) { // slide down the array looking for where we're smaller than the next guy for ($i = $size - 1; $p[$i] >= $p[$i+1]; --$i) { } // if this doesn't occur, we've finished our permutations // the array is reversed: (1, 2, 3, 4) => (4, 3, 2, 1) if ($i == -1) { return false; } // slide down the array looking for a bigger number than what we found before for ($j = $size; $p[$j] <= $p[$i]; --$j) { } // swap them $tmp = $p[$i]; $p[$i] = $p[$j]; $p[$j] = $tmp; // now reverse the elements in between by swapping the ends for (++$i, $j = $size; $i < $j; ++$i, --$j) { $tmp = $p[$i]; $p[$i] = $p[$j]; $p[$j] = $tmp; } return $p;}$set = split(' ', 'she sells seashells'); // like array('she', 'sells', 'seashells')$size = count($set) - 1;$perm = range(0, $size);$j = 0;do { foreach ($perm as $i) { $perms[$j][] = $set[$i]; }} while ($perm = pc_next_permutation($perm, $size) and ++$j);foreach ($perms as $p) { print join(' ', $p) . "n";}
