LeetCode - 202. Happy Number

题目

LeetCode - 202. Happy Number

题目链接

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

参考博客

解题思路

解题源码

class Solution {
public:
    vector<int> numsplit(int n){
      vector<int> v;
      if (!n) v.push_back(0);
      while (n){
        v.push_back(n%10);
        n /= 10;
      }
      return v;
    }
  
    bool isHappy(int n) {
      int tmp = n;
      int sum = 0;
      unordered_set<int> s; 
      s.insert(n);
      while(1){
        sum = 0;
        vector<int> v = numsplit(n);
        for (auto it : v) sum += it*it;
        if (sum == 1) return true;
        if (s.count(sum)) break;
        s.insert(sum);
        n = sum;
      }
      return false;
    }
};