829. Consecutive Numbers Sum

https://leetcode.com/problems/consecutive-numbers-sum/

Problem

Given a positive integer N, how many ways can we write it as a sum of consecutive positive integers?

Example 1:

Input: 5
Output: 2
Explanation: 5 = 5 = 2 + 3

Example 2:

Input: 9
Output: 3
Explanation: 9 = 9 = 4 + 5 = 2 + 3 + 4

Example 3:

Input: 15
Output: 4
Explanation: 15 = 15 = 8 + 7 = 4 + 5 + 6 = 1 + 2 + 3 + 4 + 5

Note: 1 <= N <= 10 ^ 9.

Solution

class Solution {
    public:
        int consecutiveNumbersSum(int N) {
            int ans = 0;
            for (int k = 1; k <= sqrt(2 * N); k++){
                if ((N - ((k + 1) * k) / 2) % k == 0) ans++;
            }
            return ans;
        }
};

• #math