count-the-number-of-good-subarrays

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Algorithms

Given an integer array <code>nums</code> and an integer <code>k</code>, return the number of good subarrays of <code>nums</code>.

A subarray <code>arr</code> is good if there are at least <code>k</code> pairs of indices <code>(i, j)</code> such that <code>i &lt; j</code> and <code>arr[i] == arr[j]</code>.

A subarray is a contiguous non-empty sequence of elements within an array.

&nbsp;
Example 1:

<pre>
Input: nums = [1,1,1,1,1], k = 10
Output: 1
Explanation: The only good subarray is the array nums itself.
</pre>

Example 2:

<pre>
Input: nums = [3,1,4,3,2,2,4], k = 2
Output: 4
Explanation: There are 4 different good subarrays:
- [3,1,4,3,2,2] that has 2 pairs.
- [3,1,4,3,2,2,4] that has 3 pairs.
- [1,4,3,2,2,4] that has 2 pairs.
- [4,3,2,2,4] that has 2 pairs.
</pre>

&nbsp;
Constraints:

<ul>
	<li><code>1 &lt;= nums.length &lt;= 105</code></li>
	<li><code>1 &lt;= nums[i], k &lt;= 109</code></li>
</ul>