C program to implement Depth First Search(DFS)


Levels of difficulty: / perform operation:

Depth First Search is an algorithm used to search the Tree or Graph. DFS search starts from root node then traversal into left child node and continues, if item found it stops other wise it continues.


The advantage of DFS is it requires less memory compare to Breadth First Search(BFS).


C Program

#include<stdio.h>
#include<conio.h>
int a[20][20],reach[20],n;
void dfs(int v) {
	int i;
	reach[v]=1;
	for (i=1;i<=n;i++)
	  if(a[v][i] && !reach[i]) {
		printf("\n %d->%d",v,i);
		dfs(i);
	}
}
void main() {
	int i,j,count=0;
	clrscr();
	printf("\n Enter number of vertices:");
	scanf("%d",&n);
	for (i=1;i<=n;i++) {
		reach[i]=0;
		for (j=1;j<=n;j++)
		   a[i][j]=0;
	}
	printf("\n Enter the adjacency matrix:\n");
	for (i=1;i<=n;i++)
	  for (j=1;j<=n;j++)
	   scanf("%d",&a[i][j]);
	dfs(1);
	printf("\n");
	for (i=1;i<=n;i++) {
		if(reach[i])
		   count++;
	}
	if(count==n)
	  printf("\n Graph is connected"); else
	  printf("\n Graph is not connected");
	getch();





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