PermMissingElem Demo Task at Codility.com

Lesson 1 – Time Complexity – PermMissingElem 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/perm_missing_elem

Solution in php:

function solution($A) {
    $N   = count($A);
    $sum = ($N + 2) * ($N + 1) / 2;
    for($i = 0; $i < $N; $i++){
        $sum -= $A[$i];
    }
    return intval($sum);
}

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