# C Program for Traversing a Directed Graph through DFS recursively, with comments displayed in output

By | 22.06.2017

## Directed Graph through DFS recursively with comments

Write a C Program for Traversing a Directed Graph through DFS recursively. Here’s simple Program for Traversing a Directed Graph through DFS recursively, with comments displayed in output.

## Depth First Search (DFS)

Depth First Search (DFS) algorithm traverses a graph in a depthward motion and uses a stack to remember to get the next vertex to start a search, when a dead end occurs in any iteration.

It employs the following rules.

• Rule 1 − Visit the adjacent unvisited vertex. Mark it as visited. Display it. Push it in a stack.
• Rule 2 − If no adjacent vertex is found, pop up a vertex from the stack. (It will pop up all the vertices from the stack, which do not have adjacent vertices.)
• Rule 3 − Repeat Rule 1 and Rule 2 until the stack is empty.

We shall not see the implementation of Depth First Traversal (or Depth First Search) in C programming language

Also Read : : C Program to implement BFS Algorithm for Connected Graph

Below is the source code for C Program for Traversing a Directed Graph through DFS recursively, with comments displayed in output which is successfully compiled and run on Windows System to produce desired output as shown below :

### SOURCE CODE : :

```/*  C Program for traversing a directed graph through DFS recursively,
with comments displayed in the output  */

#include<stdio.h>
#define MAX 100

#define initial 1
#define visited 2
#define finished 3

int n;    /*Number of vertices in the graph */
void create_graph( );

int state[MAX];

void DF_Traversal();
void DFS(int v);

int main()
{
create_graph();
DF_Traversal();
return 0;

}/*End of main()*/

void DF_Traversal()
{
int v;

for(v=0; v<n; v++)
state[v] = initial;

printf("\nEnter starting vertex for Depth First Search : ");
scanf("%d",&v);
DFS(v);
for(v=0; v<n; v++)
{
if(state[v] == initial)
DFS(v);
}
printf("\n");
}/*End of DF_Traversal( )*/

void DFS(int v)
{
int i;
state[v] = visited;
printf("\nDFS(%d) called  \n", v);

for(i=0; i<n; i++)
{
{
if(state[i] == initial )
{
printf("\n-- %d is adjacent to %d and initial\n", i, v);
DFS(i);
}
}
}
state[v] = finished;
printf("\nVertex %d finished\n", v);

}/*End of DFS()*/

void create_graph()
{
int i,max_edges,origin,destin;

printf("\nEnter number of vertices : ");
scanf("%d",&n);
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 edge!\n");
i--;
}
else
{
}
}
}```

### OUTPUT : :

```/*  C Program for traversing a directed graph through DFS recursively,
with comments displayed in the output  */

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 ) : 3 4

Enter edge 6( -1 -1 to quit ) : 2 4

Enter edge 7( -1 -1 to quit ) : -1 -1

Enter starting vertex for Depth First Search : 0

DFS(0) called

-- 1 is adjacent to 0 and initial

DFS(1) called

-- 3 is adjacent to 1 and initial

DFS(3) called

-- 4 is adjacent to 3 and initial

DFS(4) called

Vertex 4 finished

Vertex 3 finished

Vertex 1 finished

-- 2 is adjacent to 0 and initial

DFS(2) called

Vertex 2 finished

Vertex 0 finished

Process returned 0```

If you found any error or any queries related to the above program or any questions or reviews , you wanna to ask from us ,you may Contact Us through our contact Page or you can also comment below in the comment section.We will try our best to reach up to you in short interval. 