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

Credits:
Special thanks to @mithmatt and @ts for adding this problem and creating all test cases.

class Solution {
public:
//不用vector 也可以用set等直接find查詢
    bool isHappy(int n) {
        
        vector<int> res;
        int k=0,ans,f=0;
        while(f==0 && n>0){
            ans=0;
            while(n>0){
                ans+=(n%10)*(n%10);
                n/=10;
            }
            for(int i=0;i<k;i++){
                if(res[i]==ans){
                    f=1;
                    break;
                }
            }
            k++;
            res.push_back(ans);
            n=ans;
            
            if(ans==1){
                f=2;
                break;
            }
        }
        if(f==2)
            return true;
        else
            return false;
    }
};