C Exercises: Nodes from the end of a singly linked list

C Singly Linked List : Exercise-20 with Solution

Write a C program to get the n number of nodes from the end of a singly linked list.

Sample Solution:

C Code:

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

struct Node {
    int data;
    struct Node* next;
};

// Function to create a new node
struct Node* new_Node(int data) {
    struct Node* node = (struct Node*) malloc(sizeof(struct Node));
    node->data = data;
    node->next = NULL;
    return node;
}

// Function to display a linked list
void displayList(struct Node* head) {
    while (head) {
        printf("%d ", head->data);
        head = head->next;
    }
    printf("\n");
}

struct Node* Nodes_From_End(struct Node* head, int n) {
    struct Node *slow_ptr = head, *fast_ptr = head;
    int ctr = 0;

    while (fast_ptr != NULL) {
        fast_ptr = fast_ptr->next;
        if (ctr >= n) {
            slow_ptr = slow_ptr->next;
        }
        ctr++;
    }

    if (ctr < n)
        return NULL;
    return slow_ptr;
}

int main() {
    struct Node* result;
	struct Node* list1 = new_Node(1);
    list1->next = new_Node(3);
    list1->next->next = new_Node(5);
    list1->next->next->next = new_Node(7);  
    list1->next->next->next = new_Node(9); 
    list1->next->next->next = new_Node(11); 
    printf("Original list:\n");
	displayList(list1); 
	printf("Last 2 nodes from the end of the said singly list:\n");
	result = Nodes_From_End(list1,2);
    displayList(result); 
    printf("Last 3 nodes from the end of the said singly list:\n");
	result = Nodes_From_End(list1,3);
    displayList(result);
	printf("Last 4 nodes from the end of the said singly list:\n");
	result = Nodes_From_End(list1,4);
    displayList(result); 
	printf("Last 1 node from the end of the said singly list:\n");
	result = Nodes_From_End(list1,1);
    displayList(result);
	printf("Last 5 node from the end of the said singly list:\n");
	result = Nodes_From_End(list1,5);
    displayList(result);    
    return 0;
}

Sample Output:

Original list:
1 3 5 11 
Last 2 nodes from the end of the said singly list:
5 11 
Last 3 nodes from the end of the said singly list:
3 5 11 
Last 4 nodes from the end of the said singly list:
1 3 5 11 
Last 1 node from the end of the said singly list:
11 
Last 5 node from the end of the said singly list:

Flowchart :

C Programming Code Editor:

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