202. 快乐数

class Solution {
public:
    set<int>st;
    bool isHappy(int n) {
        while(n!=1){
            vector<int>ans;
            while(n>0){
                int k=n%10;
                if(k!=0)ans.push_back(k);
                n=n/10;
            }
            n=0;
            for(auto t:ans){
                n+=t*t;
            }
            if(!st.count(n))st.insert(n);
            else return false;
        }
        return true;
    }

};