breadth first search issue - c

Question

I have created a program which should read the number of vertices to be there in the graph and I have a problem in creating the links between the vertices using link list. I get it to create the vertices and it creates links between some of the nodes but for some reason, it crashes when I try to enter certain vertex as the link.
for example
if I give the number of vertices as 4
and enter inputs as 1 2 3 4 then next the vertex to link I enter 1
and the vertices to link with as -1 2 3
It crashes after I enter 3, why?
when I enter 2 as the vertex I could link with any vertices.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
struct BFS_node
{
int data,vis;
struct BFS_node *linknodes;
};
typedef struct BFS_node node;
node *head,*N=NULL;
int num;
void create_node(node **Node)
{
if(*Node==NULL)
{
*Node=(node*)malloc(sizeof(node));
head=*Node;
}
else
*Node=*Node+1;
printf("%d enter the value \n",*Node);
scanf("%d",&(*Node)->data);
(*Node)->linknodes=(node *)malloc(num*sizeof(node));
printf(" %d \n",(*Node)->linknodes);
}
node * search_node(int num,node *head2)
{
while(head2)
{
if(head2->data==num)
return head2;
head2++;
}
}
void linking()
{
node *Dnode,**Lnode;
int num,i=0;
char Snum[10];
printf("enter the number you want to link ");
scanf("%d",&num);
Dnode=search_node(num,head);
printf("%d",Dnode);
while(getchar() != '\n' && getchar()!=EOF);
Lnode=Dnode->linknodes;
printf("enter the linked numbers");
while(fgets(Snum,sizeof(Snum),stdin))
{
if(sscanf(Snum,"%d",&num)!=1)
break;
*Lnode=search_node(num,head);
printf("%d %d",Lnode,*Lnode);
Lnode++;
}
}
BFStraversal()
{
int num,i=0;
node *queue[10],*link;
printf("enter the starting number");
scanf("%d",&num);
queue[i]=search_node(num,head);
link=queue[i]->linknodes;
printf("%d",link->data);
queue[i]->vis=1;
while(queue[i]!=NULL)
{
int j=1;
link=queue[i]->linknodes;
printf("%d",queue[i]->linknodes->data);
while(link->data !=NULL)
{
if(link->vis!=1)
{
queue[i+j]=link;
link->vis=1;
j++;
}
link++;
}
printf("%d",queue[i]->data);
i++;
}
}
int main()
{
printf("enter the number of vertices \n ");
scanf("%d",&num);
for(int i=0;i<num;i++)
create_node(&N);
for(int i=0;i<num;i++)
linking();
BFStraversal();
return 0;
}

Answer 1

here is the complete working code .feels so relieved ,this was starting to annoy.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
struct BFS_node
{
int data,vis;
struct BFS_node *linknodes;
};
typedef struct BFS_node node;
node *head,*N=NULL;
int num,i=0,count=-1;
int queue[20];
void create_node(node **Node)
{
if(*Node==NULL)
{
*Node=(node*)malloc(num*sizeof(node));
head=*Node;
}
else
*Node=*Node+1;
printf(" enter the value \n");
scanf("%d",&(*Node)->data);
(*Node)->vis=1;
(*Node)->linknodes=(node *)malloc(num*sizeof(node));
printf("address- %d link- %d \n",*Node,(*Node)->linknodes);
}
node * search_node(int num,node *head2)
{
while(head2)
{
if(head2->data==num)
return head2;
head2++;
}
}
void linking()
{
node *Dnode,**Lnode;
int num2,i=0;
char Snum[10];
printf("enter the number you want to link ");
scanf("%d",&num2);
Dnode=search_node(num2,head);
while(getchar() != '\n' && getchar()!=EOF);
Lnode=Dnode->linknodes;
printf("enter the linked numbers\n");
while(fgets(Snum,sizeof(Snum),stdin))
{
node *head2=head;
if(sscanf(Snum,"%d",&num2)!=1)
break;
*Lnode=search_node(num2,head);
printf(" linknode-%d link-%d\n ",Lnode,*Lnode);
Lnode++;
}
*Lnode=0;
}
BFStraversal(int vertex)
{
node *node,*head2=head,**links;
node=search_node(vertex,head);
links=node->linknodes;
node->vis=0;
printf(" %d ",vertex);
while(*links!=0)
{
if((*links)->vis)
{
queue[i]=(*links)->data;
(*links)->vis=0;
i++;
}
links++;
}
if(++count<i)
BFStraversal(queue[count]);
}
int main()
{
printf("enter the number of vertices \n ");
scanf("%d",&num);
for(int i=0;i<num;i++)
create_node(&N);
for(int i=0;i<num;i++)
linking();
printf("enter the source vertex");
int source;
scanf("%d",&source);
BFStraversal(source);
return 0;
}
enter code here