gistfile1.php

function solution($K, $A) {
    $compliments = array();
    array_walk_recursive($A, function($current, $key) use ($K, $A, &$compliments) {
        foreach ($A as $oKey => $value) {
            if ($current + $value == $K) {
                $compliments[] = true;
            }
        }
    });
    return count($compliments);
}