Number of Subarrays With LCM Equal to K
<p>Given an integer array <code>nums</code> and an integer <code>k</code>, return <em>the number of <strong>subarrays</strong> of </em><code>nums</code><em> where the least common multiple of the subarray&#39;s elements is </em><code>k</code>.</p>

<p>A <strong>subarray</strong> is a contiguous non-empty sequence of elements within an array.</p>

<p>The <strong>least common multiple of an array</strong> is the smallest positive integer that is divisible by all the array elements.</p>

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

<pre>
<strong>Input:</strong> nums = [3,6,2,7,1], k = 6
<strong>Output:</strong> 4
<strong>Explanation:</strong> The subarrays of nums where 6 is the least common multiple of all the subarray&#39;s elements are:
- [<u><strong>3</strong></u>,<u><strong>6</strong></u>,2,7,1]
- [<u><strong>3</strong></u>,<u><strong>6</strong></u>,<u><strong>2</strong></u>,7,1]
- [3,<u><strong>6</strong></u>,2,7,1]
- [3,<u><strong>6</strong></u>,<u><strong>2</strong></u>,7,1]
</pre>

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

<pre>
<strong>Input:</strong> nums = [3], k = 2
<strong>Output:</strong> 0
<strong>Explanation:</strong> There are no subarrays of nums where 2 is the least common multiple of all the subarray&#39;s elements.
</pre>

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

<ul>
	<li><code>1 &lt;= nums.length &lt;= 1000</code></li>
	<li><code>1 &lt;= nums[i], k &lt;= 1000</code></li>
</ul>
Array; Math; Number Theory
class Solution {
public:
    int subarrayLCM(vector<int>& nums, int k) {
        int n = nums.size();
        int ans = 0;
        for (int i = 0; i < n; ++i) {
            int a = nums[i];
            for (int j = i; j < n; ++j) {
                int b = nums[j];
                int x = lcm(a, b);
                ans += x == k;
                a = x;
            }
        }
        return ans;
    }
};