FastPrep

Description

Solutions

Count the Number of Good Subarrays

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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 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 <= 10^5
1 <= nums[i], k <= 10^9