2537-count-the-number-of-good-subarrays

2537. Count the Number of Good Subarrays

Medium

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Given an integer array nums and an integer k, return the number of good subarrays of nums.

A subarray arr is good if it there are at least k pairs of indices (i, j) such that i < j and arr[i] == arr[j].

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

 

Example 1:

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

Example 2:

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.

 

Constraints:

• 1 <= nums.length <= 105
• 1 <= nums[i], k <= 109