Nesting Demo Task at Codility.com

Lesson 5 – Stacks and Queues – Nesting demo task solution code written in php. Gives 100/100 score at the time of publishing. The description of the problem is copyrighted, so please see the following link for it: https://codility.com/demo/take-sample-test/nesting

Solution in php:

function solution($S) {
    $s = preg_replace('~[^\(\)]~', '', $S);
    if($S <> $s){
        return 0;
    }
    $S = str_split($S);
    if(empty($S)){
        return 1;
    }
    $counter = 0;
    foreach($S as $v){
        switch($v){
            case '(':
                $counter++;
                break;
            case ')':
                $counter--;
                break;
        }
        if($counter < 0){
            return 0;
        }
    }
    return $counter == 0 ? 1 : 0;
}

Given “AS IS”, can be ported from other languages from solutions found on the internet, please use with care.

Please note: we think that codility.com does not give a correct assessment of your real-world programming skills. For instance, reading the below would bring more understanding why: http://codility-test-questions.blogspot.com/2013/01/my-experience-with-codility-test.html