Consecutive Numbers Sum.py

'''
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.
'''

class Solution(object):
    def consecutiveNumbersSum(self, N):
        """
        :type N: int
        :rtype: int
        """
        res = 0
        n = 1
        while N * 1.0 / n > (n - 1) * 1.0 / 2:
            a = N * 1.0 / n - (n-1) * 1.0 / 2
            if int(a) == a:
                res += 1
            n += 1
        return res