LeetCode : K-diff Pairs in an Array

Given an array of integers and an integer k, you need to find the number of unique k-diff pairs in the array. Here a k-diff pair is defined as an integer pair (i, j), where i and j are both numbers in the array and their absolute difference is k.

Example 1:

Input: [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:[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: [1, 3, 1, 5, 4], k = 0

Output: 1

Explanation: There is one 0-diff pair in the array, (1, 1).

class Solution {
public:
int findPairs(vector<int>& nums, int k) {
unordered_map<int,int>m;
int res = 0;
for(int i=0;i<nums.size();++i){
m[nums[i]]++;
}
for(auto a:m){
if(k==0&&a.second>1)
++res;
if(k>0&&m.count(a.first+k))
++res;
}
return res;
}
};