Happy Number

https://leetcode.com/problems/happy-number/

快乐数

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