Heap alogrithm implementation in PHP produces wrong results

Question

Below is a PHP function based on Heap algorithm for finding permutations. The function works fine in JavaScript but fails in PHP. Why ?

function generate($n,$A) {
    if ($n === 1) {
        var_dump($A); 
        return $A;
    } else { 
        for ($i = 0; $i < $n - 1; $i++) {
            generate($n - 1, $A); 
            if ($n % 2 === 0) {
                $t = $A[$i];
                $A[$i] = $A[$n - 1];
                $A[$n - 1] = $t;
            }else { 
                $t = $A[0];
                $A[0] = $A[$n - 1];
                $A[$n - 1] = $t; 
            }
        }
        generate($n - 1, $A);
    }
}

generate(3,array('a','b','c')); 

Output of the function should be as follows:

[ "a", "b", "c" ],
[ "b", "a", "c" ],
[ "c", "a", "b" ],
[ "a", "c", "b" ],
[ "b", "c", "a" ],
[ "c", "b", "a" ],

but I get:

[ "a", "b", "c" ],
[ "b", "a", "c" ],
[ "c", "b", "a" ],
[ "b", "c", "a" ],
[ "a", "b", "c" ],
[ "b", "a" ,"c" ] 

Answer 1

Here you go:

function swap(&$x, &$y) {
    list($x, $y) = array($y, $x);
}

function generate($n, &$A) {
    if($n === 1) {
        echo "<pre>";
        print_r($A);
        echo "</pre>";
        return $A;

    } else {

        for($i = 0; $i < $n - 1; $i++) {
            generate($n - 1, $A);
            if(($n % 2) === 0) {
                swap($A[$i], $A[$n - 1]);

            } else {
                swap($A[$n - 1], $A[0]);
            }
        }
        generate($n - 1, $A);
    }
}

$A = array('a','b','c');
generate(3, $A);