dfs using list

#include<stdio.h>

#include<conio.h>

typedef struct node

{

      struct node *next;

      int vertex;

}node;

node *G[20];

int visited[20];

int n;

void readgraph();

void insert(int,int);

void DFS(int);

void main()

{

      int i;

      readgraph();

      for(i=0;i<n;i++)

      visited[i]=0;

      DFS(0);

      getch();

}

void DFS(int i)

{

      node *p;

      printf("\n%d",i);

      p=G[i];

      visited[i]=1;

      while(p!=NULL)

      {

            i=p->vertex;

            if(!visited[i])

            DFS(i);

            p=p->next;

      }

}

void readgraph()

{

      int i,vi,vj,no;

      printf("\nEnter no. of vertices");

      scanf("%d",&n);

      for(i=0;i<n;i++)

      {

            G[i]=NULL;

            printf("\nEnter no. of edges");

            scanf("%d",&no);

            for(i=0;i<no;i++)

            {

                  printf("\nEnter an edge(u,v):");

                  scanf("%d%d",&vi,&vj);

                  insert(vi,vj);

            }

      }

}

void insert(int vi,int vj)

{

      node *p,*q;

      q=(node *)malloc(sizeof(node));

      q->vertex=vj;

      q->next=NULL;

      if(G[vi]==NULL)

      G[vi]=q;

      else

      {

            p=G[vi];

            while(p->next!=NULL)

            p=p->next;

            p->next=q;

      }

}