C Program to find Nth node from end of a singly linked list

By | 07.04.2017

Find Nth node from end of a singly linked list


Write a C Program to find Nth node from end of a singly linked list. Here’s simple Program to find Nth node from end of a singly linked list in C Programming Language.


What is Linked List ?


Linked list is a linear data structure that contains sequence of elements such that each element links to its next element in the sequence. Each link contains a connection to another link.

Following are the important terms to understand the concept of Linked List.

  • Link − Each link of a linked list can store a data called an element.
  • Next − Each link of a linked list contains a link to the next link called Next.

Each element in a linked list is called as “Node”. Each node consists of its own data and the address of the next node and forms a chain. Linked Lists are used to create trees and graphs.


Below is the source code for C Program to find Nth node from end of a singly linked list which is successfully compiled and run on Windows System to produce desired output as shown below :


SOURCE CODE : :


/* C Program to find nth node from the end of a single linked list  */

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

struct node
{
        int info;
        struct node *link;
};

struct node *create_list(struct node *start);
void display(struct node *start);
struct node *addatbeg(struct node *start,int data);
struct node *addatend(struct node *start,int data);
struct node *nthLast_node(struct node *start,int n);

int main()
{
        struct node *start=NULL, *p;
        int n;
        start=create_list(start);
        display(start);
        printf("Enter N position of node from end : ");
        scanf("%d",&n);
        p = nthLast_node(start,n);
        if(p!=NULL)
                printf("%d\n",p->info);

                return 0;

}/*End of main()*/

struct node *nthLast_node(struct node *start,int n)
{
        struct node *p1,*p2;
        int i=0;

        if(start==NULL)
                return NULL;
        p1=p2=start;

        for(i=0; i<n; i++)  /*Move the pointer p1 n times */
        {
                if(p1==NULL)
                {
                        printf("\nList has less than %d elements\n",n);
                        return NULL;
                }
                p1=p1->link;
        }

        while(p1!=NULL) /*Move both pointers till p1 becomes NULL */
        {
                p2=p2->link;
                p1=p1->link;
        }
        return p2;
}/*End of nthLast_node()*/

struct node *create_list(struct node *start)
{
        int i,n,data;
        printf("Enter the number of nodes : ");
        scanf("%d",&n);
        start=NULL;
        if(n==0)
                return start;

        printf("\nEnter the element to be inserted : ");
        scanf("%d",&data);
        start=addatbeg(start,data);

        for(i=2;i<=n;i++)
        {
                printf("\nEnter the element to be inserted : ");
                scanf("%d",&data);
                start=addatend(start,data);
        }
        return start;
}/*End of create_list()*/

void display(struct node *start)
{
        struct node *p;
        if(start==NULL)
        {
                printf("\nList is empty\n");
                return;
        }
        p=start;
        printf("\nList is :\n");
        while(p!=NULL)
        {
                printf("%d ",p->info);
                p=p->link;
        }
        printf("\n\n");
}/*End of display() */

struct node *addatbeg(struct node *start,int data)
{
        struct node *tmp;
        tmp=(struct node *)malloc(sizeof(struct node));
        tmp->info=data;
        tmp->link=start;
        start=tmp;
        return start;
}/*End of addatbeg()*/

struct node *addatend(struct node *start,int data)
{
        struct node *p,*tmp;
        tmp=(struct node *)malloc(sizeof(struct node));
        tmp->info=data;
        p=start;
        while(p->link!=NULL)
                p=p->link;
        p->link=tmp;
        tmp->link=NULL;
        return start;
}/*End of addatend()*/

OUTPUT : :


/* C Program to find nth node from the end of a single linked list  */

************** OUTPUT ****************

Enter the number of nodes : 8

Enter the element to be inserted : 1

Enter the element to be inserted : 2

Enter the element to be inserted : 3

Enter the element to be inserted : 4

Enter the element to be inserted : 5

Enter the element to be inserted : 6

Enter the element to be inserted : 7

Enter the element to be inserted : 8

List is :
1 2 3 4 5 6 7 8

Enter N position of node from end : 3
6

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