202. Happy Number

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

class Solution {public:    bool isHappy(int n) {        int m = 0;        set<int> s;        s.insert(n);        while(true){            while(n != 0){                m += (n % 10) * (n % 10);                n /= 10;            }            if(m == 1)                return true;            else if(s.count(m) != 0)                return false;            s.insert(m);            n = m;            m = 0;        }    }};