Recursive function to delete k-th node from linked list
Given a singly linked list delete node at k-th position without using loop.
Examples:
Input : list = 9->8->3->5->2->1
k = 4
Output : 9->8->3->2->1
Input : list = 0->0->1->6->2->3
k = 3
Output : 0->0->6->2->3
We recursively reduce value of k. When k reaches 1, we delete current node and return next of current node as new node. When function returns, we link the returned node as next of previous node.
C++
// Recursive CPP program to delete k-th node // of a linked list #include <bits/stdc++.h> using namespace std; struct Node { int data; struct Node* next; }; // Deletes k-th node and returns new header. Node* deleteNode(Node* start, int k) { // If invalid k if (k < 1) return start; // If linked list is empty if (start == NULL) return NULL; // Base case (start needs to be deleted) if (k == 1) { Node *res = start->next; delete(start); return res; } start->next = deleteNode(start->next, k-1); return start; } /* Utility function to insert a node at the beginning */void push(struct Node **head_ref, int new_data) { struct Node *new_node = new Node; new_node->data = new_data; new_node->next = *head_ref; *head_ref = new_node; } /* Utility function to print a linked list */void printList(struct Node *head) { while (head!=NULL) { cout << head->data << " "; head = head->next; } printf("\n"); } /* Driver program to test above functions */int main() { struct Node *head = NULL; /* Create following linked list 12->15->10->11->5->6->2->3 */ push(&head,3); push(&head,2); push(&head,6); push(&head,5); push(&head,11); push(&head,10); push(&head,15); push(&head,12); int k = 3; head = deleteNode(head, k); printf("\nModified Linked List: "); printList(head); return 0; } |
Java
// Recursive Java program to delete k-th node // of a linked list class GFG { static class Node { int data; Node next; }; // Deletes k-th node and returns new header. static Node deleteNode(Node start, int k) { // If invalid k if (k < 1) return start; // If linked list is empty if (start == null) return null; // Base case (start needs to be deleted) if (k == 1) { Node res = start.next; return res; } start.next = deleteNode(start.next, k-1); return start; } // Utility function to insert a node at the beginning / static Node push( Node head_ref, int new_data) { Node new_node = new Node(); new_node.data = new_data; new_node.next = head_ref; head_ref = new_node; return head_ref; } // Utility function to print a linked list / static void printList( Node head) { while (head!=null) { System.out.print(head.data + " "); head = head.next; } System.out.printf("\n"); } // Driver program to test above functions / public static void main(String args[]) { Node head = null; // Create following linked list //12.15.10.11.5.6.2.3 / head=push(head,3); head=push(head,2); head=push(head,6); head=push(head,5); head=push(head,11); head=push(head,10); head=push(head,15); head=push(head,12); int k = 3; head = deleteNode(head, k); System.out.printf("\nModified Linked List: "); printList(head); } } // This code is contributed by Arnab Kundu |
Python3
# Recursive Java program to delete k-th node # of a linked list class Node(object): def __init__(self, d): self.data = d self.next = None # Deletes k-th node and returns new header. def deleteNode(start, k) : # If invalid k if (k < 1) : return start # If linked list is empty if (start == None): return None # Base case (start needs to be deleted) if (k == 1) : res = start.next return res start.next = deleteNode(start.next, k - 1) return start # Utility function to insert a node # at the beginning def push(head_ref, new_data) : new_node = Node(0) new_node.data = new_data new_node.next = head_ref head_ref = new_node return head_ref # Utility function to print a linked list def printList( head) : while (head != None): print(head.data, end = " ") head = head.next print("\n") # Driver Code head = None # Create following linked list # 12.15.10.11.5.6.2.3 / head = push(head, 3) head = push(head, 2) head = push(head, 6) head = push(head, 5) head = push(head, 11) head = push(head, 10) head = push(head, 15) head = push(head, 12) k = 3head = deleteNode(head, k) print("Modified Linked List: ", end = "") printList(head) # This code is contributed by Arnab Kundu |
C#
// Recursive C# program to delete k-th node // of a linked list using System; class GFG { public class Node { public int data; public Node next; }; // Deletes k-th node and returns new header. static Node deleteNode(Node start, int k) { // If invalid k if (k < 1) return start; // If linked list is empty if (start == null) return null; // Base case (start needs to be deleted) if (k == 1) { Node res = start.next; return res; } start.next = deleteNode(start.next, k-1); return start; } // Utility function to insert a node at the beginning / static Node push( Node head_ref, int new_data) { Node new_node = new Node(); new_node.data = new_data; new_node.next = head_ref; head_ref = new_node; return head_ref; } // Utility function to print a linked list / static void printList( Node head) { while (head != null) { Console.Write(head.data + " "); head = head.next; } Console.Write("\n"); } // Driver program to test above functions / public static void Main(String []args) { Node head = null; // Create following linked list //12.15.10.11.5.6.2.3 / head=push(head,3); head=push(head,2); head=push(head,6); head=push(head,5); head=push(head,11); head=push(head,10); head=push(head,15); head=push(head,12); int k = 3; head = deleteNode(head, k); Console.Write("\nModified Linked List: "); printList(head); } } /* This code contributed by PrinciRaj1992 */ |
Output:
Modified Linked List: 12 15 11 5 6 2 3
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