Nan Mihai - Structuri de date

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

typedef struct Element
{
    struct Element *prev;
    int data;
    struct Element *next;
}Element;

typedef Element* List;

List addFirst(int value, List l)
{
    List nou;
    nou = (Element*) malloc(sizeof(Element));
    nou->prev = NULL;
    nou->data = value;
    nou->next = l;
    if(l == NULL)
    {
        l->data = value;
        l->prev = NULL;
        l->next=NULL;
    }
    else
    {
        l->prev = nou;
        l = nou;
    }
    return l;
}

List addLast(List l, int val)
{
    List nou,q;
    if (l==NULL)
    {
        l->prev = NULL;
        l->data = val;
        l->next = NULL;
    }
    else
    {
        nou=(Element *)malloc(sizeof(Element));
        q=l;
        while(q->next!=NULL)
        q=q->next;
        nou->data=val;
        nou->next=NULL;
        nou->prev=q;
        q->next=nou;
    }
    return l;
}

List delFirst(List l)
{
    if(l == NULL)
        return NULL;
    else
    {
        List nou;
        nou = l->next;
        free(l);
        l = nou;
        if(l != NULL)
        {
            l->prev = NULL;
        }
    }
    return l;
}

List delLast(List l)
{
    List temp, tmp;
    tmp = l;
    while(tmp->next != NULL)
    {
        tmp = tmp->next;
    }
    tmp->prev->next = NULL;
    free(tmp->next);
    return l;
}

void print(List l)
{
    if(l == NULL)
    {
        printf("Lista este nula!");
    }
    else
    {
        while(l->next != NULL)
        {
            printf("%d ",l->data);
            l = l->next;
        }
    }
    printf("\n");
}

List init(int val)
{
    List l;
    l = (Element *) malloc(sizeof(Element));
    l->prev = NULL;
    l->data = val;
    l->next = NULL;
    return l;
}

int main()
{
    List l;
    int x;
    scanf("%d", &x);
    l = init(x);
    l = addFirst(5, l);
    l = addFirst(6, l);
    l = addFirst(7, l);
    scanf("%d", &x);
    while(x!= 0)
    {
        l = addFirst(x, l);
        scanf("%d", &x);
    }
    l = addLast(l, 10);
    l = addLast(l, 11);
    l = addLast(l, 12);
    print(l);
    printf("Sterge primul element!\n");
    l = delFirst(l);
    print(l);
    printf("Sterge ultimul element!\n");
    l = delLast(l);
    print(l);
    return 0;
}