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C - PLUS-PLUS-ADJACENCY MATRIX CODE




Example :




#include <iostream>
#include <vector>

using namespace std;

const int V = 5;;

class AdjacencyMatrixGraph {

	public :
	
    void insertEdge(bool adjacentMatrix[][V], int i, int j) {

        adjacentMatrix[i][j] = true;
        
    }

    void removeEdge(bool adjacentMatrix[][V], int i, int j) {

        adjacentMatrix[i][j] = false;
        
    }


    void printAdjacencyMatrix(bool adjacentMatrix[][V]) {

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

            for (int j = 0; j < V; j++) {

                int val = adjacentMatrix[i][j]?1:0;
                cout << "|    " << val << "     |";
            }
            cout << endl;
        }
    }
};

    int main() {

        AdjacencyMatrixGraph adjacencyMatrixGraph;

        bool adjacentMatrix[V][V];

        //Insert Edges

        adjacencyMatrixGraph.insertEdge(adjacentMatrix, 0, 1);
        adjacencyMatrixGraph.insertEdge(adjacentMatrix, 0, 2);
        adjacencyMatrixGraph.insertEdge(adjacentMatrix, 0, 3);

        adjacencyMatrixGraph.insertEdge(adjacentMatrix, 1, 0);
        adjacencyMatrixGraph.insertEdge(adjacentMatrix, 1 ,4);

        adjacencyMatrixGraph.insertEdge(adjacentMatrix, 2, 0);
        adjacencyMatrixGraph.insertEdge(adjacentMatrix, 2, 3);
        adjacencyMatrixGraph.insertEdge(adjacentMatrix, 2, 4);

        adjacencyMatrixGraph.insertEdge(adjacentMatrix, 3, 0);
        adjacencyMatrixGraph.insertEdge(adjacentMatrix, 3 ,2);
        adjacencyMatrixGraph.insertEdge(adjacentMatrix, 3, 4);

        adjacencyMatrixGraph.insertEdge(adjacentMatrix, 4, 3);
        adjacencyMatrixGraph.insertEdge(adjacentMatrix, 4, 2);
        adjacencyMatrixGraph.insertEdge(adjacentMatrix, 4, 1);

		cout <<  "+------------------------------------------------------------+" << endl;
        adjacencyMatrixGraph.printAdjacencyMatrix(adjacentMatrix);
        cout <<  "+------------------------------------------------------------+";

    }


Output :


    

   +----------------------------------------------------------+    | 0 || 1 || 1 || 1 || 0 |    | 1 || 0 || 0 || 0 || 1 |    | 1 || 0 || 0 || 1 || 1 |    | 1 || 0 || 1 || 0 || 1 |    | 0 || 1 || 1 || 1 || 0 |    +----------------------------------------------------------+

Code explanation for Adjacency Matrix Data Structure


The code for Adjacency Matrix is quite simple.


There are two important methods defined above :

  1. void insertEdge(bool adjacentMatrix[][V], int i, int j)

  2. void removeEdge(bool adjacentMatrix[][V], int i, int j)

As the name of the method suggests insertEdge(...), is used to add an Edge to the Adjacency Matrix.


Explanation of void insertEdge(bool adjacentMatrix[][V], int i, int j) method :


void insertEdge(bool adjacentMatrix[][V], int i, int j) {

	adjacentMatrix[i][j] = true;
}

So, the actual adjacency matrix, we are going to create, looks like the below structure,

java_Collections

Now, if we look at the main(...) method. We create a 2D array, that holds either true or false.


bool adjacentMatrix[V][V];

Where, V is a constant,


	const int V = 5;

So, the above line creates a 2D array with 5 rows and 5 columns that initially contains false.

java_Collections

Now, all we need to do is, wherever we want to insert an edge. We will mark it with value true.


Say, for example :


There is an edge in [0][1] (As mentioned in the adjacency matrix above).


All we are doing is, calling the void insertEdge(...) method,


adjacencyMatrixGraph.insertEdge(adjacentMatrix, 0, 1);

and passing 0 and 1 as parameters.


And in the void insertEdge(...) method, we have the below line,


adjacentMatrix[i][j] = true;

Now, since value of i = 0 and j = 1,


adjacentMatrix[0][1] = true;

And adjacentMatrix[0][1] is marked to true.

java_Collections

In other words, we have inserted an edge in adjacentMatrix[0][1] above.


Similarly, we insert the edges one by one, calling the void insertEdge(...) method.


adjacencyMatrixGraph.insertEdge(adjacentMatrix, 0, 2);
adjacencyMatrixGraph.insertEdge(adjacentMatrix, 0, 3);
...
...
...

Explanation of void removeEdge(bool adjacentMatrix[][V], int i, int j) method :


Even, to delete an Edge, we follow the same steps.


As we know, there is an Edge in [0][2]. To remove it, all we need to do is call,


adjacencyMatrixGraph.removeEdge(adjacentMatrix, 0, 2);

And mark that particular location to false.


void removeEdge(bool adjacentMatrix[][V], int i, int j) {

	adjacentMatrix[i][j] = false;
}

And the Edge is deleted.