202. Happy Number

Write an algorithm to determine if a number n 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.
• 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.

Return true if n is a happy number, and false if not.

Example 1:

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

Example 2:

Input: n = 2
Output: false

class Solution {
public:
    int getSum(int n){
        int sum = 0;
        while(n != 0){
            sum += (n%10) * (n%10);
            n = n/10;
        }
        return sum;
    }
    bool isHappy(int n) {
        unordered_set<int> s;
        int sum = 0;
        while(1){
            int sum = getSum(n);
            if(sum == 1)
                return true;
            if(s.find(sum) != s.end())
                return false;
            s.insert(sum);
            n = sum;
        }
    }
};