333. K-diff Pairs in an Array
Medium
Unique Difference Pair Counting
Hashing
Problem
Given an integer array nums and a non-negative integer k, return the number of unique pairs of values whose absolute difference is exactly k. Pairs with the same two values count only once.
Examples
Example 1
Input: [3,1,4,1,5], 2
Output: 2
Example 2
Input: [1,2,3,4,5], 1
Output: 4
Example 3
Input: [1,3,1,5,4], 0
Output: 1
Constraints
� 1 <= nums.length <= 10000
� -10000000 <= nums[i] <= 10000000
� 0 <= k <= 10000000
Hints
?? For k greater than zero, distinct values x and x + k form one pair.
?? For k equal to zero, only values appearing at least twice form pairs.
?? A frequency map handles both cases naturally.
Expected Complexity
Time: O(n)
Space: O(n)
Follow-up
How does the k = 0 case differ from the k > 0 case?
Practice Notes
Attempts: 0
Time spent: 0min
Hints used: 0
JavaScript
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Case 1
Case 2
Case 3
Input
[3,1,4,1,5], 2Expected
2