leetcode 202. Happy Number

Seawolf

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: 

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

class Solution {

    public boolean isHappy(int n) {
        
        int sum =0;
        
        if(n == 1 || n == 7){
            
            return true;
        }
        
        else if ( n < 10){
            
            return false;
        }
        
        else{
        
        while(n > 0){
            
            sum += (n % 10) * (n % 10);
            n = n /10;

        }
        }
        return isHappy(sum);
    }
    
}