[ create a new paste ] login | about

Link: http://codepad.org/2W0GqFTN    [ raw code | output | fork ]

PHP, pasted on May 20:
<?php

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 = explode(' ', 'a b c');

// $all will contain the final output
$all = $set;
while(count($set) > 1) {
    $perms = array();
    $size = count($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) {
         $all[] = implode(' ', $p);
    }
    array_pop($set);    
}

// display results
foreach($all as $each) {
    echo $each . "\n";
}


Output:
1
2
3
4
5
6
7
8
9
10
11
a
b
c
a b c
a c b
b a c
b c a
c a b
c b a
a b
b a


Create a new paste based on this one


Comments: