K-diff Pairs in an Array — LeetCode 532 Python Solution

The problem

Given an array of integers nums and an integer k, return the number of unique k-diff pairs in the array. A k-diff pair is an integer pair (nums[i], nums[j]), where the following are true: 0 <= i, j < nums.length i != j |nums[i] - nums[j]| == k Notice that |val| denotes the absolute value of val.

Example

Input

nums = [3,1,4,1,5], k = 2

Output

2

Explanation

There are two 2-diff pairs in the array, (1, 3) and (3, 5).

Python solution

class Solution:
    def findPairs(self, nums: List[int], k: int) -> int:
        ans = set()
        vis = set()
        for x in nums:
            if x - k in vis:
                ans.add(x - k)
            if x + k in vis:
                ans.add(x)
            vis.add(x)
        return len(ans)

Complexity

Pattern: Two Pointers

Use the order already in the input to discard half the search space at every step. LeetCode 532. K-diff Pairs in an Array is filed here because LeetCode tags it Two Pointers, which is the vocabulary this hub collects.

The two pointers guide has the Python template for the pattern and the 201 LeetCode problems that use it.

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