532. K-diff Pairs in an Array.cpp

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
a <= b
b - a == k


Example 1:

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:

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:

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:

Input: nums = [1,2,4,4,3,3,0,9,2,3], k = 3
Output: 2
Example 5:

Input: nums = [-1,-2,-3], k = 1
Output: 2


Constraints:

1 <= nums.length <= 104
-107 <= nums[i] <= 107
0 <= k <= 107






class Solution {
public:
    int findPairs(vector<int>& nums, int k) {
        int cnt=0;
        set<pair<int, int> > s;
        int n=nums.size();
        sort(nums.begin(), nums.end());

        for(int i=0;i<n;i++){
            for(int j=i+1;j<n;j++){
                if(nums[i]<=nums[j] && nums[j]-nums[i]==k)
                    s.insert({nums[i], nums[j]});
            }
        }

        return s.size();
    }
};