Jednostruka2Dvostruka

#include <stdio.h>
#include <stdlib.h>
typedef struct node
{
    int data;
    struct node *next,*prev;
}NODE;
NODE *first=NULL,*last=NULL,*temp=NULL;
int isEmpty(){
    if (first==NULL) return 1;
    else return 0;
}
void create(int elem)
{
    temp=(struct node*)malloc(sizeof(struct node));
    temp->data=elem;
    temp->next=NULL;
    if(first==NULL)
    {
        first=temp;
        last=temp;
    }
    else
    {
        last->next=temp;
        last=temp;
    }

}
void display()
{
    temp=first;
    printf("First->");
    while(temp!=NULL)
    {
    //printf("|%d|%d| --> ",temp->data,temp->next);
    printf("|%d| --> ",temp->data);
    temp=temp->next;
    }
      printf("NULL\n");
}
void JeduDvo()
{
    NODE *p,*q;
    q=first;
    p=first->next;
     while(p!=NULL)
    {
        p->prev=q;
        q=p;
        p=p->next;
    }
    first->prev=NULL;
}
void display2()
{
    //printa unazad da bi videli da li je dvostruka
    temp=last->prev;
    printf("First->|%d|",last->data);
    while(temp!=NULL)
    {
    printf("<--|%d| --> ",temp->data);
    temp=temp->prev;
    }
      printf("NULL\n");
}
int main()
{
    create(1);
    create(2);
    create(3);
    create(4);
    create(5);
    display();
    JeduDvo();
    display2();
    return 0;
}