#2537
Count the Number of Good Subarrays
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array · hash table · sliding window
Description
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.
Solution