Direct graph in C: select a vertex

Hi guys.
I have tried to write a code in C for a directed graph:

Code:

---

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

#define VOL 20

/* Adjacency Matrix */
int source_vert, V, E, visited[VOL], graph[VOL][VOL];

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

int main()
{
    int i, j, vertex1, vertex2;

    printf("Directed graph\n");
    printf("Please, enter the number of vertices:\n");
    scanf("%d",&V);
    printf("Please, enter the number of edges:\n");
    scanf("%d", &E);
    for(i=0;i<V;i++)
    {
        for(j=0;j<V;j++)
            graph[i][j]=0;
    }

    /* Creating edges */
    for(i=0;i<E;i++)
    {
        printf("Please, enter the edges(format: vertex1 vertex2):");
        scanf("%d %d", &vertex1, &vertex2);
        graph[vertex1-1][vertex2-1]=1;
    }
    for(i=0;i<V;i++)
    {
        for(j=0;j<V;j++){
            printf("%d", graph[i][j]);
            printf("\n");
        }
        printf("Enter the source vertex: \n");
        scanf("%d", &source_vert);
        dfs(source_vert-1);
    }
    return 0;
}

---

Something was wrong.
My adjacency matrix is not a proper matrix, but an array :(
Furthermore, I need to select a vertex, in order to randomly select a new neighbour for it.
Could you please help me? Thank you.

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