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
public class Solution { private int getNextHappy(int n) { int sum = 0; while (n != 0) { sum += (n % 10) * (n % 10); n /= 10; } return sum; } public boolean isHappy(int n) { HashSet<Integer> hash = new HashSet<Integer>(); while (n != 1) { if (hash.contains(n)) { return false; } hash.add(n); n = getNextHappy(n); } return true; } }