Consecutive Numbers Sum
<p>Given an integer <code>n</code>, return <em>the number of ways you can write </em><code>n</code><em> as the sum of consecutive positive integers.</em></p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> n = 5
<strong>Output:</strong> 2
<strong>Explanation:</strong> 5 = 2 + 3
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> n = 9
<strong>Output:</strong> 3
<strong>Explanation:</strong> 9 = 4 + 5 = 2 + 3 + 4
</pre>

<p><strong class="example">Example 3:</strong></p>

<pre>
<strong>Input:</strong> n = 15
<strong>Output:</strong> 4
<strong>Explanation:</strong> 15 = 8 + 7 = 4 + 5 + 6 = 1 + 2 + 3 + 4 + 5
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= n &lt;= 10<sup>9</sup></code></li>
</ul>
Math; Enumeration
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
}