Question

829. Consecutive Numbers Sum

中文文档

Description

Given an integer n, return _the number of ways you can write _n_ as the sum of consecutive positive integers._

 

Example 1:

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

Example 2:

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

Example 3:

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

 

Constraints:

• 1 <= n <= 109

Solutions

Solution 1

class Solution:
  def consecutiveNumbersSum(self, n: int) -> int:
    n <<= 1
    ans, k = 0, 1
    while k * (k + 1) <= n:
      if n % k == 0 and (n // k + 1 - k) % 2 == 0:
        ans += 1
      k += 1
    return ans

class Solution {

  public int consecutiveNumbersSum(int n) {
    n <<= 1;
    int ans = 0;
    for (int k = 1; k * (k + 1) <= n; ++k) {
      if (n % k == 0 && (n / k + 1 - k) % 2 == 0) {
        ++ans;
      }
    }
    return ans;
  }
}

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

func consecutiveNumbersSum(n int) int {
  n <<= 1
  ans := 0
  for k := 1; k*(k+1) <= n; k++ {
    if n%k == 0 && (n/k+1-k)%2 == 0 {
      ans++
    }
  }
  return ans
}