lab test set a er a 24-02-20

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

typedef struct data
{
    int a;

    struct data *next;
    struct data *prev;
} data;

data *head=NULL;
data *tail=NULL;

void ins_at_first(int x)
{
    data *new_node=(data*)malloc(sizeof(data));
    new_node->a=x;
    new_node->next=NULL;
    new_node->prev=NULL;

    if(head==NULL)
    {
        head=new_node;
        return;
    }
    new_node->next=head;
    head->prev=NULL;
    head=new_node;

    return;
}
void ins_new_node(int x)
{

    data *new_node=(data*)malloc(sizeof(data));
    new_node->a=x;
    new_node->next=NULL;
    new_node->prev=NULL;

    data *temp=head;

    while(temp->a!=7)
    {
        temp=temp->next;
    }
    new_node->next=temp->next;
    new_node->prev=temp;
    temp->next=new_node;
    temp->next->prev=new_node;
    return;
}

void print()
{
    data *temp=head;

    while(temp!=NULL)
    {
        printf("%d ",temp->a);
        temp=temp->next;
    }
    printf("\n");
}



int main()
{
    ins_at_first(9);
    ins_at_first(5);
    ins_at_first(7);
    ins_at_first(3);
    ins_at_first(2);
    ins_at_first(4);

    print();
    ins_new_node(666);
    print();
}