*DFS Algorithm for Connected Graph*

*DFS Algorithm for Connected Graph*

Write a C Program to implement DFS Algorithm for Connected Graph. Here’s simple Program for traversing a directed graph through Depth First Search(DFS), visiting only those vertices that are reachable from start vertex.

**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 to implement DFS Algorithm for Connected Graph which is successfully compiled and run on Windows System to produce desired output as shown below :

**SOURCE CODE : :**

**SOURCE CODE : :**

/* C Program to implement DFS Algorithm for Connected Graph */ #include<stdio.h> #include<stdlib.h> #define MAX 100 #define initial 1 #define visited 2 int n; /* Number of nodes in the graph */ int adj[MAX][MAX]; /*Adjacency Matrix*/ int state[MAX]; /*Can be initial or visited */ void DF_Traversal(); void DFS(int v); void create_graph(); int stack[MAX]; int top = -1; void push(int v); int pop(); int isEmpty_stack(); main() { create_graph(); DF_Traversal(); }/*End of main()*/ void DF_Traversal() { int v; for(v=0; v<n; v++) state[v]=initial; printf("\nEnter starting node for Depth First Search : "); scanf("%d",&v); DFS(v); printf("\n"); }/*End of DF_Traversal( )*/ void DFS(int v) { int i; push(v); while(!isEmpty_stack()) { v = pop(); if(state[v]==initial) { printf("%d ",v); state[v]=visited; } for(i=n-1; i>=0; i--) { if(adj[v][i]==1 && state[i]==initial) push(i); } } }/*End of DFS( )*/ void push(int v) { if(top == (MAX-1)) { printf("\nStack Overflow\n"); return; } top=top+1; stack[top] = v; }/*End of push()*/ int pop() { int v; if(top == -1) { printf("\nStack Underflow\n"); exit(1); } else { v = stack[top]; top=top-1; return v; } }/*End of pop()*/ int isEmpty_stack( ) { if(top == -1) return 1; else return 0; }/*End if isEmpty_stack()*/ void create_graph() { int i,max_edges,origin,destin; printf("\nEnter number of nodes : "); 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 { adj[origin][destin] = 1; } } }

**OUTPUT : :**

**OUTPUT : :**

/* C Program to implement DFS Algorithm for Connected Graph */ Enter number of nodes : 6 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 ) : 4 2 Enter edge 7( -1 -1 to quit ) : 5 5 Enter edge 8( -1 -1 to quit ) : -1 -1 Enter starting node for Depth First Search : 0 0 1 3 4 2 Process returned 0

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**Recommended Posts : :**

**Recommended Posts : :**

- BFS Algorithm for Connected Graph
- BFS Algorithm for Disconnected Graph
- Connected Components in an Undirected Graph
- Path Matrix by Warshall’s Algorithm
- Path Matrix by powers of Adjacency matrix

can you explain ??

both are same .its your choice .our aim is to chose any unvisited adjacent node of current node

Thank you!!! It helped me so much