K-Diff Pairs In An Array Problem
Description
LeetCode Problem 532.
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
- |nums[i] - nums[j]| == k
Notice that |val| denotes the absolute value of val.
Example 1:
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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). Although we have two 1s in the input, we should only return the number of unique pairs.
Example 2:
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Input: nums = [1,2,3,4,5], k = 1
Output: 4
Explanation: There are four 1-diff pairs in the array, (1, 2), (2, 3), (3, 4) and (4, 5).
Example 3:
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Input: nums = [1,3,1,5,4], k = 0
Output: 1
Explanation: There is one 0-diff pair in the array, (1, 1).
Example 4:
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Input: nums = [1,2,4,4,3,3,0,9,2,3], k = 3
Output: 2
Example 5:
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2
Input: nums = [-1,-2,-3], k = 1
Output: 2
Constraints:
- 1 <= nums.length <= 10^4
- -10^7 <= nums[i] <= 10^7
- 0 <= k <= 10^7
Sample C++ Code
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class Solution {
public:
int findPairs(vector<int>& A, int k) {
unordered_map<int, int> m;
for (int n : A) m[n]++;
int ans = 0;
for (auto &[n, cnt] : m) {
ans += k ? m.count(n - k) : cnt > 1;
}
return ans;
}
};