happynumber.js

/*
Write an algorithm to determine if a number n is happy.

A happy number is a number defined by the following process:

Starting with any positive integer, replace the number by the sum of the squares of its digits.
Repeat the process until the number equals 1 (where it will stay), or it loops endlessly in a cycle which does not include 1.
Those numbers for which this process ends in 1 are happy.
Return true if n is a happy number, and false if not.

Example 1:
Input: n = 19
Output: true
Explanation:
12 + 92 = 82
82 + 22 = 68
62 + 82 = 100
12 + 02 + 02 = 1

Example 2:
Input: n = 2
Output: false
*/

/**
 * @param {number} n
 * @return {boolean}
 */
var isHappy = function (n) {
    let output = false;
    let vals = [];
    function isHappy(n) {
        let x = n.toString().split("");
        x.map(num => Number(num));
        let y = x.map(num => num * num);
        let sum = y.reduce((item, total) => item + total);
        if (sum == 1) {
            output = true;
        } else {
            if (!vals.includes(sum)) {
                vals.push(sum);
                isHappy(sum)
            } else {
                output = false;
            }
        }
    }

    if (n == 1) {
        output = true
    } else if (n > 1) {
        isHappy(n);
    }
    return output
};