202. Happy Number.cpp

/*
Problem Description:
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
*/

class Solution {
public:
    bool isHappy(int n) {
        while(n>0)
        {
            n=count_square(n);
            if(n==1)
            {
                return true;
            }
            if(n==4)
            {
                return false;
            }
        }
        return false;
    }
    
    int count_square(int n)
    {
        int sum=0;
        while(n!=0)
        {
            sum+=pow(n%10,2);
            n/=10;
        }
        return sum;
    }
};