leetcode829 连续整数求和

思路：

数论。参考了https://leetcode.cn/problems/consecutive-numbers-sum/solution/by-ac_oier-220q/。

实现：

 1 class Solution {
 2 public:
 3     int consecutiveNumbersSum(int n) {
 4         int res=0;
 5         for(int i=1;i*i<2*n;i++){
 6             if(2*n%i==0){
 7                 int j=2*n/i-i+1;
 8                 if(j%2==0 and j>=2){
 9                     res++;
10                 }
11             }
12         }
13         return res;
14     }
15 };