happy-number.js

/**
 * Source:  https://leetcode.com/problems/happy-number/
 * Tags:    [Hash Table,Math]
 * Level:   Easy
 * Updated: 2015-04-24
 * Title:   Happy Number
 * Auther:  @imcoddy
 * Content: Write an algorithm to determine if a number 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, and 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 numbers.
 *
 * Example: 19 is a happy number
 *
 *
 * 12 + 92 = 82
 * 82 + 22 = 68
 * 62 + 82 = 100
 * 12 + 02 + 02 = 1
 *
 *
 * Credits:Special thanks to @mithmatt and @ts for adding this problem and creating all test cases.
 */

/**
 * @param {number} n
 * @return {boolean}
 */
var isHappy = function(n) {
    var result = n;
    var map = {};
    // map[n] = 1;
    result = getResult(result);
    map[result] = 1;
    while (result !== 1) {
        result = getResult(result);
        if (map[result]) {
            return false;
        } else {
            map[result] = 1;
            n = result;
        }
    }
    return true;
};

var getResult = function(n) {
    var result = 0;
    while (n) {
        var d = n % 10;
        result += d * d;
        n = Math.floor(n / 10);
    }
    return result;
};

console.log(getResult(1933));
console.log(isHappy(0));
console.log(isHappy(10));
console.log(isHappy(11));