题目

happy-number

算法

* 直接模拟

* set

代码

* 直接模拟

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

* set

class Solution {
public:
    bool isHappy(int n) {
        while (n != 1 && n != 4) {
            int t = 0;
            while (n) {
                t += (n % 10) * (n % 10);
                n /= 10;
            }
            n = t;
        }
        return n == 1;
    }
};