dsa/DLL.cpp at main · intrinsi/dsa · GitHub

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#include <stdio.h>

#include <stdlib.h>

struct node {

    int num;

    struct node * preptr;

    struct node * nextptr;

}*stnode, *ennode;


void DlListcreation(int n);

void displayDlListRev();

int main()

{

    int n;

    stnode = NULL;

    ennode = NULL;

	printf("\n\n Doubly Linked List : Create and display a doubly linked list in reverse order :\n");	printf("------------------------------------------------------------------------------------\n");

    printf(" Input the number of nodes : ");

    scanf("%d", &n);


    DlListcreation(n);

    displayDlListRev();

    return 0;

}


void DlListcreation(int n)

{

    int i, num;

    struct node *fnNode;


    if(n >= 1)

    {

        stnode = (struct node *)malloc(sizeof(struct node));


        if(stnode != NULL)

        {

            printf(" Input data for node 1 : "); // assigning data in the first node

            scanf("%d", &num);


            stnode->num = num;

            stnode->preptr = NULL;

            stnode->nextptr = NULL;

            ennode = stnode;

// putting data for rest of the nodes

            for(i=2; i<=n; i++)

            {

                fnNode = (struct node *)malloc(sizeof(struct node));

                if(fnNode != NULL)

                {

                    printf(" Input data for node %d : ", i);

                    scanf("%d", &num);

                    fnNode->num = num;

                    fnNode->preptr = ennode;    // new node is linking with the previous node

                    fnNode->nextptr = NULL;


                    ennode->nextptr = fnNode;   // previous node is linking with the new node

                    ennode = fnNode;            // assign new node as last node

                }

                else

                {

                    printf(" Memory can not be allocated.");

                    break;

                }

            }

        }

        else

        {

            printf(" Memory can not be allocated.");

        }

    }

}

void displayDlListRev()

{

    struct node * tmp;

    int n = 0;


    if(ennode == NULL)

    {

        printf(" No data found in the List yet.");

    }

    else

    {

        tmp = ennode;

        printf("\n Data in reverse order are :\n");

        while(tmp != NULL)

        {

            printf(" Data in node %d : %d\n", n+1, tmp->num);

            n++;

            tmp = tmp->preptr; // current pointer set with previous node

        }

    }

}