1 min read
https://practice.geeksforgeeks.org/problems/count-pairs-with-given-sum5022/1
class Solution {
public:
int getPairsCount(int arr[], int n, int k) {
map<int, int> mp;
for (int i = 0; i < n; i++)
mp[arr[i]]++;
int ctr = 0;
for (int i = 0; i < n; i++) {
ctr += mp[k - arr[i]];
if (k - arr[i] == arr[i])
ctr--;
}
return ctr / 2;
}
};