Delete Nth node from the end of the given linked list

Given a linked list and an integer N, the task is to delete the N^th node from the end of the given linked list.

Examples:

Input: 2 -> 3 -> 1 -> 7 -> NULL, N = 1
Output:
Created Linked list is:
2 3 1 7
Linked List after Deletion is:
2 3 1

Input: 1 -> 2 -> 3 -> 4 -> NULL, N = 4
Output:
Created Linked list is:
1 2 3 4
Linked List after Deletion is:
2 3 4

Recommended: Please try your approach on {IDE} first, before moving on to the solution.

Approach:

Take two pointers, first will point to the head of the linked list and second will point to the N^th node from the beginning.
Now keep increment both the pointers by one at the same time until second is pointing to the last node of the linked list.
After the operations from the previous step, first pointer should be pointing to the N^th node from the end by now. So, delete the node first pointer is pointing to.

Below is the implementation of the above approach:

C++

// C++ implementation of the approach 
#include<bits/stdc++.h> 
using namespace std; 
  
class LinkedList 
{ 
    public: 
      
    // Linked list Node 
    class Node 
    { 
        public: 
        int data; 
        Node* next; 
        Node(int d) 
        { 
            data = d; 
            next = NULL; 
        } 
    }; 
      
    // Head of list 
    Node* head; 
  
    // Function to delete the nth node from 
    // the end of the given linked list 
    Node* deleteNode(int key) 
    { 
  
        // First pointer will point to 
        // the head of the linked list 
        Node *first = head; 
  
        // Second pointer will poin to the 
        // Nth node from the beginning 
        Node *second = head; 
        for (int i = 0; i < key; i++) 
        { 
  
            // If count of nodes in the given 
            // linked list is <= N 
            if (second->next == NULL)  
            { 
  
                // If count = N i.e. 
                // delete the head node 
                if (i == key - 1) 
                    head = head->next; 
                return head; 
            } 
            second = second->next; 
        } 
  
        // Increment both the pointers by one until 
        // second pointer reaches the end 
        while (second->next != NULL) 
        { 
            first = first->next; 
            second = second->next; 
        } 
  
        // First must be pointing to the 
        // Nth node from the end by now 
        // So, delete the node first is pointing to 
        first->next = first->next->next; 
        return head; 
    } 
  
    // Function to insert a new Node  
    // at front of the list 
    Node* push(int new_data) 
    { 
        Node* new_node = new Node(new_data); 
        new_node->next = head; 
        head = new_node; 
        return head; 
    } 
  
    // Function to print the linked list 
    void printList() 
    { 
        Node* tnode = head; 
        while (tnode != NULL)  
        { 
            cout << (tnode->data) << ( " "); 
            tnode = tnode->next; 
        } 
    } 
}; 
  
// Driver code 
int main() 
{ 
    LinkedList* llist = new LinkedList(); 
  
    llist->head = llist->push(7); 
    llist->head = llist->push(1); 
    llist->head = llist->push(3); 
    llist->head = llist->push(2); 
  
    cout << ("Created Linked list is:\n"); 
    llist->printList(); 
  
    int N = 1; 
    llist->head = llist->deleteNode(N); 
  
    cout << ("\nLinked List after Deletion is:\n"); 
    llist->printList(); 
} 
  
// This code is contributed by Arnab Kundu  

Java

// Java implementation of the approach 
class LinkedList { 
  
    // Head of list 
    Node head; 
  
    // Linked list Node 
    class Node { 
        int data; 
        Node next; 
        Node(int d) 
        { 
            data = d; 
            next = null; 
        } 
    } 
  
    // Function to delete the nth node from 
    // the end of the given linked list 
    void deleteNode(int key) 
    { 
  
        // First pointer will point to 
        // the head of the linked list 
        Node first = head; 
  
        // Second pointer will poin to the 
        // Nth node from the beginning 
        Node second = head; 
        for (int i = 0; i < key; i++) { 
  
            // If count of nodes in the given 
            // linked list is <= N 
            if (second.next == null) { 
  
                // If count = N i.e. delete the head node 
                if (i == key - 1) 
                    head = head.next; 
                return; 
            } 
            second = second.next; 
        } 
  
        // Increment both the pointers by one until 
        // second pointer reaches the end 
        while (second.next != null) { 
            first = first.next; 
            second = second.next; 
        } 
  
        // First must be pointing to the 
        // Nth node from the end by now 
        // So, delete the node first is pointing to 
        first.next = first.next.next; 
    } 
  
    // Function to insert a new Node at front of the list 
    public void push(int new_data) 
    { 
        Node new_node = new Node(new_data); 
        new_node.next = head; 
        head = new_node; 
    } 
  
    // Function to print the linked list 
    public void printList() 
    { 
        Node tnode = head; 
        while (tnode != null) { 
            System.out.print(tnode.data + " "); 
            tnode = tnode.next; 
        } 
    } 
  
    // Driver code 
    public static void main(String[] args) 
    { 
        LinkedList llist = new LinkedList(); 
  
        llist.push(7); 
        llist.push(1); 
        llist.push(3); 
        llist.push(2); 
  
        System.out.println("\nCreated Linked list is:"); 
        llist.printList(); 
  
        int N = 1; 
        llist.deleteNode(N); 
  
        System.out.println("\nLinked List after Deletion is:"); 
        llist.printList(); 
    } 
} 

Python3

# Python3 implementation of the approach 
class Node:  
    def __init__(self, new_data):  
        self.data = new_data  
        self.next = None
class LinkedList: 
    def __init__(self): 
        self.head = None
  
    # createNode and and make linked list  
    def push(self, new_data):  
        new_node = Node(new_data)  
        new_node.next = self.head  
        self.head = new_node  
  
    def deleteNode(self, n): 
        first = self.head 
        second = self.head 
        for i in range(n): 
              
            # If count of nodes in the  
            # given list is less than 'n' 
            if(second.next == None): 
                  
                # If index = n then  
                # delete the head node 
                if(i == n - 1): 
                    self.head = self.head.next
                return self.head 
            second = second.next
          
        while(second.next != None): 
            second = second.next
            first = first.next
          
        first.next = first.next.next
      
    def printList(self): 
        tmp_head = self.head 
        while(tmp_head != None): 
            print(tmp_head.data, end = ' ') 
            tmp_head = tmp_head.next
          
# Driver Code 
llist = LinkedList()  
llist.push(7)  
llist.push(1)  
llist.push(3)  
llist.push(2)  
print("Created Linked list is:") 
llist.printList() 
llist.deleteNode(1)  
print("\nLinked List after Deletion is:") 
llist.printList() 
  
# This code is contributed by RaviParkash 

C#

// C# implementation of the approach 
using System; 
      
public class LinkedList 
{ 
  
    // Head of list 
    public Node head; 
  
    // Linked list Node 
    public class Node  
    { 
        public int data; 
        public Node next; 
        public Node(int d) 
        { 
            data = d; 
            next = null; 
        } 
    } 
  
    // Function to delete the nth node from 
    // the end of the given linked list 
    void deleteNode(int key) 
    { 
  
        // First pointer will point to 
        // the head of the linked list 
        Node first = head; 
  
        // Second pointer will poin to the 
        // Nth node from the beginning 
        Node second = head; 
        for (int i = 0; i < key; i++)  
        { 
  
            // If count of nodes in the given 
            // linked list is <= N 
            if (second.next == null)  
            { 
  
                // If count = N i.e. delete the head node 
                if (i == key - 1) 
                    head = head.next; 
                return; 
            } 
            second = second.next; 
        } 
  
        // Increment both the pointers by one until 
        // second pointer reaches the end 
        while (second.next != null)  
        { 
            first = first.next; 
            second = second.next; 
        } 
  
        // First must be pointing to the 
        // Nth node from the end by now 
        // So, delete the node first is pointing to 
        first.next = first.next.next; 
    } 
  
    // Function to insert a new Node at front of the list 
    public void push(int new_data) 
    { 
        Node new_node = new Node(new_data); 
        new_node.next = head; 
        head = new_node; 
    } 
  
    // Function to print the linked list 
    public void printList() 
    { 
        Node tnode = head; 
        while (tnode != null) 
        { 
            Console.Write(tnode.data + " "); 
            tnode = tnode.next; 
        } 
    } 
  
    // Driver code 
    public static void Main(String[] args) 
    { 
        LinkedList llist = new LinkedList(); 
  
        llist.push(7); 
        llist.push(1); 
        llist.push(3); 
        llist.push(2); 
  
        Console.WriteLine("\nCreated Linked list is:"); 
        llist.printList(); 
  
        int N = 1; 
        llist.deleteNode(N); 
  
        Console.WriteLine("\nLinked List after Deletion is:"); 
        llist.printList(); 
    } 
} 
  
// This code is contributed by 29AjayKumar 

Output:

Created Linked list is:
2 3 1 7 
Linked List after Deletion is:
2 3 1

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My Personal Notes

Recommended: Please try your approach on {IDE} first, before moving on to the solution.

C++

Java

Python3

C#

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