Tower of Hanoi

hanoi.js

/**
 * Thst is not the optimal formula, don't use it.
 * This is just another solution for the algorithm
 * Tower of Hanoi.
 */

if (Array.prototype.last === undefined) {
    Array.prototype.last = function () {
        return this.length ? this[this.length - 1] : 0;
    };
};

var a = [3, 2, 1],
    b = [],
    c = [],
    counter = 0;

function swap(a1, a2) {
    a1.push(a2.pop());
}

function compareAndReplace(a1, a2) {
    if (!a1.length && !a2.length) {
        return;
    }

    if (!a2.last()) {
        swap(a2, a1);
        return true;
    }

    if (!a1.last()) {
        swap(a1, a2);
        return true;
    }

    if (a1.last() > a2.last()) {
        swap(a1, a2);
    }
    else {
        swap(a2, a1);
    }

    return true;
}

function towerOfHanoi(a, b, c) {
    if (!a.length && !b.length) {
        return [a, b, c];
    }

    compareAndReplace(a, b) && logger(a, b, c);
    compareAndReplace(a, c) && logger(a, b, c);
    compareAndReplace(b, c) && logger(a, b, c);

    return towerOfHanoi(a, b, c);
}

function logger(lists) {
    ++counter && console.log(counter, '>', 'A:', a, 'B:', b, 'C:', c);
}

towerOfHanoi(a, b, c);