Advent Of Code - Day 10

by Uzair Mehmood

JavaScript

var num = '1113122113';
var applyTimes = 50;

function lookAndSay(num) {
    var look = /(.)\1*/g;
    function say(match) {
        return match.length.toString() + match.substring(0, 1);
    }

    return num.replace(look, say);
}

for (var i=1; i<=applyTimes; i++) {
    num = lookAndSay(num);
}

alert(num.length);