DLL_ques.c

/*This program take a DLL as input which has 10 positive and 10 negative number in random order and provide 2 DLL as output. One DLL for positive integers & other for negative integers.*/
#include <stdio.h>
#include <stdlib.h>
typedef struct node{                   // doubly linked node
    int info;
    struct Node* next;         // points to next node
    struct Node* prev;     // points to previous node
}node;

node * addtoempty(node * start, int n)
{
    node * tmp;
    tmp = (node *)malloc(sizeof(node));
    tmp->info = n;
    tmp->prev = NULL;
    tmp->next = NULL;
    start = tmp;
    return start;
}//end of addtoempty

node * addtoend(node * start, int data)
{
    node * tmp, *ptr;
    tmp = (node *)malloc(sizeof(node));
    tmp->info = data;
    ptr=start; //now we have to traverse to find the end location
    while(ptr->next != NULL)
        ptr = ptr->next;
    ptr->next=tmp;
    tmp->prev=ptr;
    tmp->next=NULL;
    return start;
}//end of addtoend
node * createlist(node * start, int data)
{
    if (start == NULL)
        {
            start = addtoempty(start,data);
            return start;

        }
    else
        {
            start = addtoend(start,data);
            return start;
        }


    //return start;



}//end of create list

void bifurcatelist(node * start)
{
    node * ptr, *p_start = NULL, *n_start = NULL;
    ptr = start;
    while(ptr!=NULL)
        {
            if(ptr->info < 0)
                {
                    n_start = createlist(n_start,ptr->info);
                }
            else
                p_start = createlist(p_start,ptr->info);
            ptr= ptr->next;
        }
    printf("\n\nThe positive linked list is following:  \n");
    display(p_start);
    printf("\n\nThe negative linked list is following: \n");
    display(n_start);

}//end of bifurcatelist

void display(node * start)
{
    node * ptr;
    ptr = start;
    while(ptr!=NULL)
        {
            printf("%3d ",ptr->info);
            ptr = ptr->next;
        }
}//end of display


int main()
{   node * start=NULL;


    int i,data;
    printf("Please enter 10 positive & 10 negative numbers in random order: \n");

    for ( i = 1; i <= 20; i++)
    {
        printf("Enter the nuber %d:  \n",i);
        scanf("%d",&data);
        start = createlist(start,data);
    }
   printf("\n\n Here is your list:  \n");
    display(start);
    printf("\n\nHere is your bifurcated lists:  \n");
    bifurcatelist(start);
    return 0;
}