StoneWall (sigma2012) Demo Task at Codility.com

Lesson 5 – Stacks and Queues – StoneWall (sigma2012) 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/stone_wall

Solution in php:

function solution($H) {
    $N         = count($H);
    $stones    = 0;
    $stack     = array_fill(0, $N, 0);
    $stack_num = 0;

    for($i = 0; $i  0 && $stack[$stack_num - 1] > $H[$i]){
            $stack_num--;
        }
        if($stack_num > 0 && $stack[$stack_num - 1] == $H[$i]){
            continue;
        }
        else{
            $stones++;
            $stack[$stack_num++] = $H[$i];
        }
    }
    return $stones;
}

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

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