graphdb.c

#include <stdio.h>
#include <stdlib.h>

int source,V,E,visited[20],G[20][20],Q[20],f=-1,r=-1;

void DFS(int i){
    int j;
    visited[i]=1;
    printf("%d->",i);
    for(j=1;j<=V;j++){
        if(G[i][j]==1 && visited[j]==0){
            DFS(j);
        }
    }
}

void enqueue(int item){
    if(f==-1 && r==-1){
        f=r=0;
        Q[r]=item;
    }
    else{
        r++;
        Q[r]=item;
    }
}

int dequeue(){
    int item;
    if(f==-1 && r==-1){
        printf("Queue is empty\n");
        return -1;
    }
    else if(f==r){
        item=Q[f];
        f=r=-1;
        return item;
    }
    else{
        item=Q[f];
        f++;
        return item;
    }
}

void BFS(int s){
    int i;
    visited[s]=1;
    printf("%d->",s);
    enqueue(s);

    while(f!=-1){
        s=dequeue();
        for(i=1;i<=V;i++){
            if(G[s][i]==1 && visited[i]==0){
                printf("%d->",i);
                visited[i]=1;
                enqueue(i);
            }
        }
    }
}

void main(){
    int i,j,v1,v2,opt;
    printf("\t\t\tGraphs\n");
    printf("Enter the number of vertices : ");
    scanf("%d",&V);
    for(i=1;i<=V;i++){
        for(j=1;j<=V;j++){
            G[i][j]=0;
        }
    }

    printf("Enter the number of edges: ");
    scanf("%d",&E);
    for(i=1;i<=E;i++){
        printf("Enter the edges (format: V1 V2) : ");
        scanf("%d%d",&v1,&v2);
        G[v1][v2]=1;
        G[v2][v1]=1;
    }
    printf("The Adjacency Matrix is : \n");
    for(i=1;i<=V;i++){
        for(j=1;j<=V;j++){
            printf("%d\t",G[i][j]);
        }
        printf("\n");
    }
    for (i=1;i<=V;i++){
        visited[i]=0;
    }
    printf("Enter the Source : ");
    scanf("%d",&source);
    printf("DFS Traversal is: ");
    DFS(source);
    printf("\n");
    for(i=1;i<=V;i++){
        visited[i]=0;
    }
    printf("BFS Traversal is: ");
    BFS(source);
    printf("\n");
}