Pairs with difference K

 

You are given with an array of integers and an integer K. You have to find and print the count of all such pairs which have difference K.

Note: Take absolute difference between the elements of the array.

Input Format:

The first line of input contains an integer, that denotes the value of the size of the array. Let us denote it with the symbol n.
The following line contains n space separated integers, that denote the value of the elements of the array.
The following line contains an integer, that denotes the value of K.

Output format :

The first and only line of output contains count of all such pairs which have an absolute difference of K. 

Constraints :

0 <= n <= 10^4
Time Limit: 1 sec

Sample Input 1 :

4 
5 1 2 4
3

Sample Output 1 :

2

Sample Input 2 :

4
4 4 4 4 
0

Sample Output 2 :

6

#include <unordered_map>
int getPairsWithDifferenceK(int *arr, int n, int k) {
    // Write your code here
    
    unordered_map <int,int> st;
    int ans = 0;
    
    for (int i=0;i<n;i++){ 
        // num - comp = k
        // comp = num - k || k- num
        
            if (st.count(k+arr[i])){
                ans += st[k+arr[i]];
            }
        
            else if (st.count(arr[i]-k)){
                ans += st[arr[i]-k];
            }
            st[arr[i]]++;
    }
    
    return ans;
}