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
Credits:
Special thanks to @mithmatt and @ts for adding this problem and creating all test cases.
public class Solution { public boolean isHappy(int n) { int newNum = 0 ; HashSet<Integer> set = new HashSet<Integer>(); while(!set.contains(n)){ set.add(newNum); newNum = 0; while(n != 0){ newNum += (n%10) * (n%10); n = n/10; } n = newNum; if(n == 1) return true; } return false; } }