equal_stacks.js

// Source - https://www.hackerrank.com/challenges/equal-stacks/problem

// Solution by user "manjula dube" - See comment at https://www.youtube.com/watch?v=X9NdolHDm2c&lc=Ugx3ya8xOB2wAj1Oi154AaABAg

function equalStacks(h1, h2, h3) {
    /*
     * Write your code here.
     */

    // get the sum of each stack
    var height1 = h1.reduce(function(a, b){return a+b;});
    var height2 = h2.reduce(function(a, b){return a+b;});
    var height3 = h3.reduce(function(a, b){return a+b;});

    while(!(height1 === height2 && height1 === height3)) {
        var discarded_block = 0;
        if((height1 > height2) && (height1 > height3)){
            discarded_block = h1.shift();
            height1 = height1 - discarded_block;
        } else if((height2 > height1) && (height2 > height3)) {
            discarded_block = h2.shift();
            height2 = height2 - discarded_block;
        } else if((height3 > height1) && (height3 > height2)) {
            discarded_block = h3.shift();
            height3 = height3 - discarded_block;   
        } else if((height1 > height3) && (height1 === height2)) { 
            // 1 and 2 are greater than 3
            discarded_block = h1.shift();
            height1 = height1 - discarded_block;   
        } else if((height2 > height1) && (height2 === height3)) { 
            // 2 and 3 are greater than 1
            discarded_block = h2.shift();
            height2 = height2 - discarded_block;
        } else if((height1 > height2) && (height1 === height3)){ 
            // 1 and 3 are greater than 2
            discarded_block = h3.shift();
            height3 = height3 - discarded_block;
        }
    }
    return height1
}