# Write a C Program for Creation of Adjacency Matrix

By | 11.05.2017

Write a C Program for Creation of Adjacency Matrix. Here’s simple Program for adjacency matrix representation of graph in data structure in C Programming Language.

Adjacency Matrix is a 2D array of size V x V where V is the number of vertices in a graph. Let the 2D array be adj[][], a slot adj[i][j] = 1 indicates that there is an edge from vertex i to vertex j.

Adjacency matrix for undirected graph is always symmetric. Adjacency Matrix is also used to represent weighted graphs. If adj[i][j] = w, then there is an edge from vertex i to vertex j with weight w.

Pros: Representation is easier to implement and follow. Removing an edge takes O(1) time. Queries like whether there is an edge from vertex ‘u’ to vertex ‘v’ are efficient and can be done O(1).

Cons: Consumes more space O(V^2). Even if the graph is sparse(contains less number of edges), it consumes the same space. Adding a vertex is O(V^2) time.

Check Out : : How to Print Spiral Order Traversal of a Binary Tree

Below is the source code for C Program for Creation of Adjacency Matrix which is successfully compiled and run on Windows System to produce desired output as shown below :

### SOURCE CODE : :

```/*  C Program for creation of adjacency matrix */

#include<stdio.h>
#define MAX 100

int n;    /*Number of vertices in the graph*/

int main()
{
int max_edges,i,j,origin,destin;
int graph_type;

printf("\nEnter 1 for Undirected graph\nEnter 2 for Directed graph\n");
scanf("%d",&graph_type);

printf("\nEnter number of vertices :: ");
scanf("%d",&n);

if(graph_type==1)
max_edges = n*(n-1)/2;
else
max_edges = n*(n-1);

for(i=1; i<=max_edges; i++)
{
printf("\nEnter edge [ %d ] ( -1 -1 to quit ) : ",i);
scanf("%d %d",&origin,&destin);
if( (origin == -1) && (destin == -1) )
break;
if( origin>=n || destin>=n || origin<0 || destin<0 )
{
printf("\nInvalid vertex!\n");
i--;
}
else
{
if( graph_type == 1) /*if undirected graph*/
}
}/*End of for*/

printf("\nThe adjacency matrix is :: \n");
for(i=0; i<=n-1; i++)
{
for(j=0; j<=n-1; j++)
printf("\n");
}
}/*End of main()*/```

### OUTPUT : :

```/*  C Program for Creation of Adjacency matrix  */

Enter 1 for Undirected graph
Enter 2 for Directed graph

Enter number of vertices :: 5

Enter edge [ 1 ] ( -1 -1 to quit ) : 0 1

Enter edge [ 2 ] ( -1 -1 to quit ) : 0 2

Enter edge [ 3 ] ( -1 -1 to quit ) : 0 3

Enter edge [ 4 ] ( -1 -1 to quit ) : 1 3

Enter edge [ 5 ] ( -1 -1 to quit ) : 2 3

Enter edge [ 6 ] ( -1 -1 to quit ) : 3 4

Enter edge [ 7 ] ( -1 -1 to quit ) : 4 2

Enter edge [ 8 ] ( -1 -1 to quit ) : -1 -1

0   1   1   1   0
0   0   0   1   0
0   0   0   1   0
0   0   0   0   1
0   0   1   0   0

Process returned 0```

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