public class Solution
extends Object
992 - Subarrays with K Different Integers\.
Hard
Given an integer array `nums` and an integer `k`, return _the number of **good subarrays** of_ `nums`.
A **good array** is an array where the number of different integers in that array is exactly `k`.
* For example, `[1,2,3,1,2]` has `3` different integers: `1`, `2`, and `3`.
A **subarray** is a **contiguous** part of an array.
**Example 1:**
**Input:** nums = [1,2,1,2,3], k = 2
**Output:** 7
**Explanation:** Subarrays formed with exactly 2 different integers: [1,2], [2,1], [1,2], [2,3], [1,2,1], [2,1,2], [1,2,1,2]
**Example 2:**
**Input:** nums = [1,2,1,3,4], k = 3
**Output:** 3
**Explanation:** Subarrays formed with exactly 3 different integers: [1,2,1,3], [2,1,3], [1,3,4].
**Constraints:**
* 1 <= nums.length <= 2 * 104
* `1 <= nums[i], k <= nums.length`