LeetCode-Happy Number

Posted 2020-07-07 IncredibleThings

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 {
    public boolean isHappy(int n) {
        Set<Integer> numberSet = new HashSet<Integer>();
        while(n!=1){
            if(!numberSet.add(n)){
                return false;
            }
            char[] chars = String.valueOf(n).toCharArray();
            int total = 0;
            for(Character ch: chars){
                total += Math.pow(Integer.parseInt(ch+""),2);
            }
            n = total;
        }
        return true;
    }
}