map of int and pair

map<pair<int, int>, int> vis; 
// Print positions that are not marked as visited 
void printPositions(int a[3][3]) 
{ 
    for (int i = 0; i < 3; i++) 
        for (int j = 0; j < 3; j++) 
            if (vis[{ i, j }] == 0) 
                cout << "(" << i << ", " << j << ")"
                     << "\n"; 
} 
int main() 
{ 
    int mat[3][3] = { { 0, 1, 2 }, { 3, 4, 5 }, { 6, 7, 8 } }; 
    // Marking some positions as visited 
    vis[{ 0, 0 }] = 1; // visit (0, 0) 
    vis[{ 1, 0 }] = 1; // visit (1, 0) 
    vis[{ 1, 1 }] = 1; // visit (1, 1) 
    vis[{ 2, 2 }] = 1; // visit (2, 2) 
    // print which positions in matrix are not visited by rat 
    printPositions(mat); 
    return 0; 
}