Adjacency Matrix and Adjacency List of connected Graph

Question

Suppose in a social media network:

N is friends with K, P, U, X
X is friends with N, A, B and C
U is friends with A, B and N
A is friends with P, U and X
B is friends with X and U
P is friends with K, N and A
K is friends with P, N and M
M is friends with C, N and K

Solve the following problems in c++
a. Write a function to print the adjacency matrix in 2D array and also you have to Draw the final graph
b. Write a function to print the non connected friends list for everyone.
I solved question number (a) as per the requirement of the problem. I am not sure what the question number (b) is asking for.

Answer 1

The solution to problems a and b is the following:

#include <iostream>
using namespace std;

class Graph {
    int v;
    int** adj;

public:
    Graph(int v);
    void addEdge(int start, int e);
    void printMatrix();
    void nonConnected(int start);
};

Graph::Graph(int v)
{
    this->v = v;
    adj = new int*[v];
    for (int row = 0; row < v; row++) {
        adj[row] = new int[v];
        for (int column = 0; column < v; column++) {
            adj[row][column] = 0;
        }
    }
}

// Add an edge to the graph
void Graph::addEdge(int i, int j) {
    adj[i][j] = 1;
    adj[j][i] = 1;
}

// Print the Matrix
  void Graph::printMatrix() {
    for (int i = 0; i < v; i++) {
      cout << i << " : ";
      for (int j = 0; j < v; j++)
        cout << adj[i][j] << " ";
      cout << "\n";
    }
  }

  char friends(int n) {
    if(n == 0) {
        return 'N';
    }
    else if(n == 1) {
        return 'X';
    }
    else if(n == 2) {
        return 'U';
    }
    else if(n == 3) {
        return 'A';
    }
    else if(n == 4) {
        return 'B';
    }
    else if(n == 5) {
        return 'P';
    }
    else if(n == 6) {
        return 'K';
    }
    else if(n == 7) {
        return 'M';
    }
    else {
        return 'C';
    }
  }

void Graph::nonConnected(int start)
{

    cout << friends(start) << " is not friends with: " ;

    for (int i = 0; i < v; i++) {

        if (adj[start][i] == 0 and i != start) {
            cout << friends(i) << " ";
        }
    }
    printf("\n");
}

// Driver code
int main()
{
    int v = 9;
    char arr[9] = {'N', 'X', 'U', 'A', 'B', 'P', 'K', 'M', 'C'};

    // Create the graph
    Graph G(v);
    // friends of N
    G.addEdge(0, 1);
    G.addEdge(0, 2);
    G.addEdge(0, 5);
    G.addEdge(0, 6);

    //friends of X
    G.addEdge(1, 0);
    G.addEdge(1, 3);
    G.addEdge(1, 4);
    G.addEdge(1, 8);

    //friends of U
    G.addEdge(2, 0);
    G.addEdge(2, 3);
    G.addEdge(2, 4);

    //friends of A
    G.addEdge(3, 1);
    G.addEdge(3, 2);
    G.addEdge(3, 5);

    //friends of B
    G.addEdge(4, 1);
    G.addEdge(4, 2);

    //friends of P
    G.addEdge(5, 0);
    G.addEdge(5, 3);
    G.addEdge(5, 6);

    //friends of k
    G.addEdge(6, 0);
    G.addEdge(6, 5);
    G.addEdge(6, 7);

    // friends of M
    G.addEdge(7, 0);
    G.addEdge(7, 6);
    G.addEdge(7, 8);

    // friends of C
    G.addEdge(8, 1);
    G.addEdge(8, 6);

    G.printMatrix();

    G.nonConnected(0);
    G.nonConnected(1);
    G.nonConnected(2);
    G.nonConnected(3);
    G.nonConnected(4);
    G.nonConnected(5);
    G.nonConnected(6);
    G.nonConnected(7);
    G.nonConnected(8);
}