prac_linklist

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

struct node
{
   int data;
   int key;

   struct node *next;
   struct node *prv;
};
struct node *head=NULL;

void insert(int data,int key)
{

    struct node *temp=(struct node*)malloc(sizeof(struct node));
    temp->data=data;
    temp->key=key;

    if(head==NULL)
    {
        temp->next=NULL;
        head=temp;
        return;
    }
    struct node *temp1=head;
    while(temp1->next!=NULL)
    {
        temp1=temp1->next;
    }

    temp1->next=temp;
    temp->next=NULL;

}

void print( )
{
    struct node *ptr=head;

    while(ptr!=NULL)
    {
        printf("DATA:%d\t KEY:%d\n",ptr->data,ptr->key);
        ptr=ptr->next;
    }
}
int length()
{
    int len=0;
    struct node *temp=head;
    while(temp!=NULL)
    {
        len++;
        temp=temp->next;
    }
    return len;
}

void in_pos(int data,int key,int n)
{

    struct node *temp=(struct node*)malloc(sizeof(struct node));
    temp->data=data;
    temp->key=key;
    if(n==1)
    {
        temp->next=head;
        head=temp;
        return;
    }

    int size=length();

    if((size+1)<n)
    {
        printf("Can't insert in this position\n");
        return ;
    }

    struct node *cur=head;
    int i;
    for(i=0;i<(n-2);i++)
    {
        cur=cur->next;
    }

    temp->next=cur->next;
    cur->next=temp;

}

void delete_first()
{


    if(head==NULL)
    {
        printf("Can't delete no elements assigned\n");
        return;
    }
    head=head->next;

}

void last_delete()
{

    struct node* cur=head,*prv=NULL;
    while(cur->next!=NULL)
    {
        prv=cur;
        cur=cur->next;
    }

    prv->next=NULL;




}

void delete_nth(int n)
{

    int size=length();
    if(size<n)
    {
        printf("No elements in this position\n");
        return;
    }

    if(n==1)
    {
        head=head->next;
        return;
    }
    int i;
    struct node *cur=head,*temp;
    for(i=0;i<n-2;i++)
    {
        cur=cur->next;
    }
    temp=cur->next;
    cur->next=temp->next;
    free(temp);

}

void del_key(int key)
{
    if((head->key)==key)
    {
        head=head->next;
        return;
    }
    struct node *cur=head,*prv=NULL;
    while(cur->key!=key)
    {
        if(cur->next==NULL)
            return NULL;

        prv=cur;
        cur=cur->next;
    }
    prv->next=cur->next;
    free(cur);

}

int main()
{
   insert(10,12);
   insert(13,14);
   insert(16,18);
   insert(20,18);
   int size=length();
   printf("%d\n",size);
   print();

   in_pos(11,12,1);
   in_pos(12,100,4);
   in_pos(100,111,10);
   insert(11,111111);
   size=length();

   printf("%d\n",size);

   print();
   printf("\n");
   delete_first();
   delete_first();
   size=length();
   printf("%d\n",size);
   print();
   last_delete();
   size=length();
   printf("%d\n",size);
   print();
   delete_nth(2);
   printf("\n");
   print();
   del_key(14);
   printf("\n");
   print();

}