Count all pairs with given XOR in C++

In this tutorial, we will be discussing a program to find the number of pairs with the given XOR.

For this we will be provided with an array and a value. Our task is to find the number of pairs whose XOR is equal to the given value.

Example

#include<bits/stdc++.h>
using namespace std;
//returning the number of pairs
//having XOR equal to given value
int count_pair(int arr[], int n, int x){
   int result = 0;
   //managing with duplicate values
   unordered_map<int, int> m;
   for (int i=0; i<n ; i++){
      int curr_xor = x^arr[i];
      if (m.find(curr_xor) != m.end())
         result += m[curr_xor];
      m[arr[i]]++;
   }
   return result;
}
int main(){
   int arr[] = {2, 5, 2};
   int n = sizeof(arr)/sizeof(arr[0]);
   int x = 0;
   cout << "Count of pairs with given XOR = " << count_pair(arr, n, x);
   return 0;
}

Output

Count of pairs with given XOR = 1