C Program to Find Nth Node from End of Linked List

This C Program prints the Nth node from the last node of a linked list. The approach used is to first point a pointer to a node which is N nodes ahead from the head. Then, move the Nth pointer and head pointer one node at a time till the Nth pointer has reached to the rear node. The pointer in the middle is the Nth pointer from the end.

Here is a source code of the C program to print the nth node from the last node of a linked list. The C program is successfully compiled and run on a Linux system. The program output is also shown below.

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/*
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 * C Program to Print Nth Node from the last of a Linked List

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 */
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#include <stdio.h>
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#include <stdlib.h>
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struct node
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{
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    int num;
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    struct node *next;
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};
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void create(struct node **);
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void nthnode(struct node *, int);
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void release(struct node **);
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int main()
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{
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    struct node *p = NULL;
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    int n;
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    printf("Enter data into the list\n");

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    create(&p);
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    printf("Enter the value n to find nth position from the last node: ");

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    scanf("%d", &n);
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    nthnode(p, n);
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    release (&p);
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```
 
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    return 0;
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}
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```
 
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void nthnode(struct node *head, int n)
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{
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    struct node *p, *q;
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    int i;
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    q = p = head;
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    for (i = 0; i < n && q != NULL; i++)

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    {
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        q = q->next;
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    }
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    if (i < n)
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    {
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        printf("Entered n = %d is larger than the number of elements = %d in list. Please try again.\n", n, i);

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    }
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    else
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    {
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        while (q->next != NULL)
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        {
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            q = q->next;
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            p = p->next;
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        }
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        printf("%d is %d nodes from the last node.\n", p->num, n);

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    }
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}
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void create(struct node **head)
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{
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    int c, ch;
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    struct node *temp, *rear;
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    do
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    {
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        printf("Enter number: ");
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        scanf("%d", &c);
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        temp = (struct node *)malloc(sizeof(struct node));

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        temp->num = c;
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        temp->next = NULL;
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        if (*head == NULL)
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        {
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            *head = temp;
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        }
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        else
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        {
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            rear->next = temp;
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        }
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        rear = temp;
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        printf("Do you wish to continue [1/0]: ");

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        scanf("%d", &ch);
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    } while (ch != 0);
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    printf("\n");
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}
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void release(struct node **head)
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{
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    struct node *temp = *head;
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    *head = (*head)->next;
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    while ((*head) != NULL)
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    {
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        free(temp);
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        temp = *head;
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        (*head) = (*head)->next;
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    }
```
```
}
```

$ cc nthnode.c 
$ ./a.out
Enter data into the list
Enter number: 1
Do you wish to continue [1/0]: 1
Enter number: 2
Do you wish to continue [1/0]: 1
Enter number: 3
Do you wish to continue [1/0]: 1
Enter number: 4
Do you wish to continue [1/0]: 1
Enter number: 5
Do you wish to continue [1/0]: 0
 
Enter the value n to find nth position from the last node: 2
3 is 2 nodes from the last node.