cpp-gfg/Count pairs Sum in matrices at master · avinashbest/cpp-gfg · GitHub

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// { Driver Code Starts
#include <bits/stdc++.h>
using namespace std;


 // } Driver Code Ends


//User function template for C++
class Solution{
public:

	int countPairs(vector<vector<int>> &mat1, vector<vector<int>> &mat2, int n, int x)
	{
	    int count = 0;

    // unordered_set 'us' implemented as hash table
    unordered_set<int> us;

    // insert all the elements of mat2[][] in 'us'
    for (int i = 0; i < n; i++)
        for (int j = 0; j < n; j++)
            us.insert(mat2[i][j]);

    // for each element of mat1[][]
    for (int i = 0; i < n; i++)
        for (int j = 0; j < n; j++)

            // if (x-mat1[i][j]) is in 'us'
            if (us.find(x - mat1[i][j]) != us.end())
                count++;

    // required count of pairs
    return count;
	}
};

// { Driver Code Starts.


int main()
{

   	ios_base::sync_with_stdio(0);
    cin.tie(NULL);
    cout.tie(NULL);

   	int t;
    cin >> t;
    while (t--)
    {
        int n, x;
        cin >> n >> x;

        vector<vector<int>> mat1(n, vector<int>(n, -1));
        vector<vector<int>> mat2(n, vector<int>(n, -1));

        for(int i = 0; i < n; i++)
        {
        	for(int j = 0; j < n; j++)
        	{
        		cin >> mat1[i][j];
        	}
        }

        for(int i = 0; i < n; i++)
        {
        	for(int j = 0; j < n; j++)
        	{
        		cin >> mat2[i][j];
        	}
        }

        Solution ob;

        cout << ob.countPairs(mat1, mat2, n, x) << "\n";

    }

    return 0;
}  // } Driver Code Ends