Program to delete all even nodes from a Singly Linked List
Given a singly linked list containing N nodes, the task is to delete all the even nodes from the list.
Examples:
Input: LL = 1 -> 4 -> 3 -> 18 -> 19
Output: 1 -> 3 -> 19
Input: LL = 5 -> 3 -> 6 -> 8 -> 4 -> 1 -> 2 -> 9
Output: 5 -> 3 -> 1 -> 9
Approach 1:
- The idea is to traverse the nodes of the singly linked list one by one and get the pointer of the nodes having even data. Delete those nodes by following the approach used in this post.
Below is the implementation of the above idea:
C++
// C++ implementation to delete all // even nodes from the singly linked list #include <bits/stdc++.h> using namespace std; // Node of the singly linked list struct Node { int data; struct Node* next; }; // Function to insert a node at // the beginning of the singly // Linked List void push( struct Node** head_ref, int new_data) { struct Node* new_node = ( struct Node*) malloc ( sizeof ( struct Node)); new_node->data = new_data; new_node->next = (*head_ref); (*head_ref) = new_node; } // Function to delete a node in a // singly Linked List. // head_ref --> Pointer to head // node pointer. // key --> Node to be deleted void deleteNode( struct Node** head_ref, int key) { // Store head node struct Node *temp = *head_ref, *prev; // If head node itself holds // the key to be deleted if (temp != NULL && temp->data == key) { // Changed head *head_ref = temp->next; return ; } // Search for the key to be // deleted, keep track of the // previous node as we need // to change 'prev->next' while (temp != NULL && temp->data != key) { prev = temp; temp = temp->next; } // If key was not present // in linked list if (temp == NULL) return ; // Unlink the node from // linked list prev->next = temp->next; } // Function to delete all the // even nodes from the // singly linked list void deleteEvenNodes(Node** head_ref) { Node* ptr = *head_ref; // Node* next; while (ptr != NULL) { // next = ptr->next; // If true, delete node 'ptr' if (ptr->data % 2 == 0) deleteNode(head_ref, ptr->data); ptr = ptr->next; } } // This function prints contents // of linked list starting from // the given node void printList( struct Node* node) { while (node != NULL) { printf ( " %d -> " , node->data); node = node->next; } } // Driver code int main() { // Start with the empty list Node* head = NULL; push(&head, 19); push(&head, 18); push(&head, 3); push(&head, 4); push(&head, 1); printf ( "Initial List: " ); printList(head); deleteEvenNodes(&head); printf ( "\nFinal List: " ); printList(head); } |
Java
// Java implementation to delete all // even nodes from the singly linked list 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 insert a node at // the beginning of the singly // Linked List public void push( int new_data) { Node new_node = new Node(new_data); new_node.next = head; head = new_node; } // Function to delete a node in a // singly Linked List. void deleteNode( int key) { // Store head node Node temp = head, prev = null ; // If head node itself holds the // key to be deleted if (temp != null && temp.data == key) { // Changed head head = temp.next; return ; } // Search for the key to be deleted, // keep track of the previous node // as we need to change temp.next while (temp != null && temp.data != key) { prev = temp; temp = temp.next; } // If key was not present in linked list if (temp == null ) return ; // Unlink the node from linked list prev.next = temp.next; } // Function to delete all the nodes // from linked list containing // even numbers. void deleteEvenNodes() { Node ptr = head; // loop to iterate the linked list while (ptr != null ) { // If containing element is even if (ptr.data % 2 == 0 ) { // Delete the node deleteNode(ptr.data); } ptr = ptr.next; } } // This function prints contents of linked // list starting from the given node public void printList() { Node ptr = head; while (ptr != null ) { System.out.print(ptr.data + "-> " ); ptr = ptr.next; } } // Driver code public static void main(String[] args) { LinkedList head = new LinkedList(); head.push( 19 ); head.push( 18 ); head.push( 3 ); head.push( 4 ); head.push( 1 ); System.out.print( "\nInitial List: " ); head.printList(); head.deleteEvenNodes(); System.out.print( "\nFinal List: " ); head.printList(); } } // This code is contributed by Amit Mangal |
Python3
# Python3 implementation to delete all # even nodes from the singly linked list # Node class class Node: # Function to initialize the node object def __init__( self , data): # Assign data self .data = data # Initialize # next as null self . next = None # Linked List Class class LinkedList: # Function to initialize the # LinkedList class. def __init__( self ): # Initialize head as None self .head = None # This function insert a new node at # the beginning of the linked list def push( self , new_data): # Create a new Node new_node = Node(new_data) # Make next of new Node as head new_node. next = self .head # Move the head to point to new Node self .head = new_node # Method to print the linked list def printList( self ): # Object to iterate # the list ptr = self .head # Loop to iterate list while (ptr ! = None ): print (ptr.data, '-> ' , end = '') # Moving the iterating object # to next node ptr = ptr. next print () # Method to delete a node in # a singly linked list. def deleteNode( self , key): temp = self .head # If head node itself holds # the key to be deleted. if (temp ! = None and temp.data = = key): # Changing head of list. self .head = temp. next return # Search for the key to be # deleted, keep track of the # previous node as we need # to change prev.next while (temp ! = None and temp.data ! = key): prev = temp temp = temp. next # If is not present in list if (temp = = None ): return # Unlink the node from # linked list prev. next = temp. next # Method to delete all the # even nodes from singly # linked list. def deleteEvenNodes( self ): ptr = self .head # Loop to iterate the # linked list. while (ptr ! = None ): # If node contains even number. if (ptr.data % 2 = = 0 ): # Deleting the node self .deleteNode(ptr.data) ptr = ptr. next # Driver code if __name__ = = '__main__' : head = LinkedList() # Pushing elements at start # of linked list. head.push( 19 ) head.push( 18 ) head.push( 3 ) head.push( 4 ) head.push( 1 ) # Print initial linked list print ( "Initial list: " , end = '') head.printList() # Calling the function to delete # nodes containing even numbers. head.deleteEvenNodes() # Print the final list print ( "Final list: " , end = '') head.printList() # This code is contributed by Amit Mangal |
C#
// C# implementation to delete all // even nodes from the singly linked list using System; class List{ // head of list Node head; // Linked list Node public class Node { public int data; public Node next; public Node( int d) { data = d; next = null ; } } // Function to insert a node at // the beginning of the singly // Linked List public void push( int new_data) { Node new_node = new Node(new_data); new_node.next = head; head = new_node; } // Function to delete a node in a // singly Linked List. void deleteNode( int key) { // Store head node Node temp = head, prev = null ; // If head node itself holds the // key to be deleted if (temp != null && temp.data == key) { // Changed head head = temp.next; return ; } // Search for the key to be deleted, // keep track of the previous node // as we need to change temp.next while (temp != null && temp.data != key) { prev = temp; temp = temp.next; } // If key was not present // in linked list if (temp == null ) return ; // Unlink the node from // linked list prev.next = temp.next; } // Function to delete // all the nodes from // linked list containing // even numbers. void deleteEvenNodes() { Node ptr = head; // loop to iterate the linked list while (ptr != null ) { // If containing element is even if (ptr.data % 2 == 0) { // Delete the node deleteNode(ptr.data); } ptr = ptr.next; } } // This function prints contents of linked // list starting from the given node public void printList() { Node ptr = head; while (ptr != null ) { Console.Write(ptr.data + "-> " ); ptr = ptr.next; } } // Driver code public static void Main(String []args) { List head = new List(); head.push(19); head.push(18); head.push(3); head.push(4); head.push(1); Console.Write( "\nInitial List: " ); head.printList(); head.deleteEvenNodes(); Console.Write( "\nFinal List: " ); head.printList(); } } // This code contributed by gauravrajput1 |
Javascript
<script> // javascript implementation to delete all // even nodes from the singly linked list // head of list var head; // Linked list Node class Node { constructor(val) { this .data = val; this .next = null ; } } // Function to insert a node at // the beginning of the singly // Linked List function push(new_data) { var new_node = new Node(new_data); new_node.next = head; head = new_node; } // Function to delete a node in a // singly Linked List. function deleteNode(key) { // Store head node var temp = head, prev = null ; // If head node itself holds the // key to be deleted if (temp != null && temp.data == key) { // Changed head head = temp.next; return ; } // Search for the key to be deleted, // keep track of the previous node // as we need to change temp.next while (temp != null && temp.data != key) { prev = temp; temp = temp.next; } // If key was not present in linked list if (temp == null ) return ; // Unlink the node from linked list prev.next = temp.next; } // Function to delete all the nodes // from linked list containing // even numbers. function deleteEvenNodes() { var ptr = head; // loop to iterate the linked list while (ptr != null ) { // If containing element is even if (ptr.data % 2 == 0) { // Delete the node deleteNode(ptr.data); } ptr = ptr.next; } } // This function prints contents of linked // list starting from the given node function printList() { var ptr = head; while (ptr != null ) { document.write(ptr.data + "-> " ); ptr = ptr.next; } } // Driver code push(19); push(18); push(3); push(4); push(1); document.write( "<br/>Initial List: " ); printList(); deleteEvenNodes(); document.write( "<br/>Final List: " ); printList(); // This code contributed by aashish1995 </script> |
Initial List: 1 -> 4 -> 3 -> 18 -> 19 -> Final List: 1 -> 3 -> 19 ->
Time Complexity: O(N^2)
As the complexity of deleteNode function is O(N) and we need to call it for every even number.
Auxiliary Space: O(1)
As constant extra space is used.
Approach 2:
The idea is to traverse the linked list one by one and get the pointer of nodes having even values. Also keep deleting the nodes having even values using the method used in this post.
We want the time complexity to be O(1) for deleting a given node in order to get O(N) solution for overall approach.
The algorithm for the deleteNode function:
- In the deleteNode function we get the pointer of the node to be deleted directly.
- Copy the value of next node’s to this node.
- delete the next node.
The only thing to keep in mind is that the node to be deleted should not be the last node if we are using the above method to delete the node, but it gives the result in O(1) time so we will use this in our solution.
The algorithm for the deleteEvenNodes function:
- We get the head of the linked list as a function parameter.
- Use dummy pointer variables ptr and prev which are used to store the current and previous node respectively.
- Traverse the linked list before last element using a while loop and do the following:
- delete the nodes with odd values and keep updating the prev and ptr pointers
- The case of last node is handled explicitly at the end.
Full implementation of above approach:
C++
// C++ implementation to delete all // even valued nodes from the singly linked list #include <bits/stdc++.h> using namespace std; // Node of the singly linked list struct Node { int data; struct Node* next; }; // Function to insert a node at // the beginning of the singly // Linked List void push( struct Node** head_ref, int new_data) { struct Node* new_node = ( struct Node*) malloc ( sizeof ( struct Node)); new_node->data = new_data; new_node->next = (*head_ref); (*head_ref) = new_node; } // Function to delete a node in a // singly Linked List. // node --> Pointer to given node void deleteNode( struct Node* node) { // copy the next node's value in current node node->data = node->next->data; // store the pointer to node's next in a temp variable struct Node* temp = node->next; // connect the node with node's next's next node->next = node->next->next; // delete the temp delete (temp); } // Function to delete all the // even valued nodes from the // singly linked list void deleteEvenNodes(Node** head_ref) { Node* ptr = *head_ref; Node* prev; // mark the current head with ptr pointer while (ptr != NULL && ptr->next != NULL) { // traverse the linked list before the last element if (ptr->data % 2 == 0) deleteNode(ptr); // delete the node if the value of the node is even else { prev = ptr; ptr = ptr->next; } // move the pointer to the next element and store // the prev node } if (ptr == *head_ref && ptr->data % 2 == 0) *head_ref = NULL; else if (ptr->data % 2 == 0) { prev->next = NULL; delete ptr; } } // This function prints contents // of linked list starting from // the given node void printList( struct Node* node) { while (node != NULL) { printf ( " %d -> " , node->data); node = node->next; } } // Driver code int main() { // Start with the empty list Node* head = NULL; push(&head, 2); push(&head, 6); push(&head, 15); push(&head, 16); push(&head, 18); printf ( "Initial List: " ); printList(head); deleteEvenNodes(&head); printf ( "\nFinal List: " ); printList(head); } // This code was contributed by Abhijeet Kumar |
Java
// Java implementation to delete all // even valued nodes from the singly linked list 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 insert a node at // the beginning of the singly // Linked List public void push( int new_data) { Node new_node = new Node(new_data); new_node.next = head; head = new_node; } // Function to delete a node in a // singly Linked List. void deleteNode(Node node) { // copy the next node's value in current node node.data = node.next.data; // connect the node with node's next's next node.next = node.next.next; } // Function to delete all the nodes // from linked list containing // even numbers. void deleteEvenNodes() { Node ptr = head; Node prev = null ; //mark the current head with ptr pointer while (ptr!= null && ptr.next != null ) { // traverse the linked list before the last element if (ptr.data % 2 == 0 ) deleteNode(ptr); // delete the node if the value of the node is even else { prev = ptr; ptr = ptr.next; } // move the pointer to the next element and store the previous pointer } if (ptr==head && ptr.data % 2 == 0 ) head = null ; else if (ptr.data % 2 == 0 ) prev.next = null ; } // This function prints contents of linked // list starting from the given node public void printList() { Node ptr = head; while (ptr != null ) { System.out.print(ptr.data + "-> " ); ptr = ptr.next; } } // Driver code public static void main(String[] args) { LinkedList head = new LinkedList(); head.push( 2 ); head.push( 6 ); head.push( 15 ); head.push( 16 ); head.push( 18 ); System.out.print( "\nInitial List: " ); head.printList(); head.deleteEvenNodes(); System.out.print( "\nFinal List: " ); head.printList(); } } // This code is contributed by Abhijeet Kumar(abhijeet19403) |
Python3
# Python3 implementation to delete all # even valued nodes from the singly linked list # Node class class Node: # Function to initialize the node object def __init__( self , data): # Assign data self .data = data # Initialize # next as null self . next = None # Linked List Class class LinkedList: # Function to initialize the # LinkedList class. def __init__( self ): # Initialize head as None self .head = None # This function insert a new node at # the beginning of the linked list def push( self , new_data): # Create a new Node new_node = Node(new_data) # Make next of new Node as head new_node. next = self .head # Move the head to point to new Node self .head = new_node # Method to print the linked list def printList( self ): # Object to iterate # the list ptr = self .head # Loop to iterate list while (ptr ! = None ): print (ptr.data, '-> ' , end = '') # Moving the iterating object # to next node ptr = ptr. next print () # Method to delete a node in # a singly linked list. def deleteNode( self ,node): # copy the next node's value in current node node.data = node. next .data # connect the node with node's next's next node. next = node. next . next # Method to delete all the # even valued nodes from singly # linked list. def deleteEvenNodes( self ): #mark the current head with ptr pointer ptr = self .head prev = self .head # traverse the linked list before the last element while (ptr! = None and ptr. next ! = None ): # delete the node if the value of the node is even if (ptr.data % 2 = = 0 ): self .deleteNode(ptr) # move the pointer to the next element and store the previous pointer else : prev = ptr ptr = ptr. next if (ptr = = self .head and ptr.data % 2 = = 0 ): head = None elif (ptr.data % 2 = = 0 ): prev. next = None # Driver code if __name__ = = '__main__' : head = LinkedList() # Pushing elements at start # of linked list. head.push( 18 ) head.push( 16 ) head.push( 15 ) head.push( 6 ) head.push( 2 ) # Print initial linked list print ( "Initial list: " , end = '') head.printList() # Calling the function to delete # nodes containing even numbers. head.deleteEvenNodes() # Print the final list print ( "Final list: " , end = '') head.printList() # This code is contributed by Abhijeet Kumar(abhijeet19403) |
C#
// C# implementation to delete all // even valued nodes from the singly linked list using System; class List{ // head of list Node head; // Linked list Node public class Node { public int data; public Node next; public Node( int d) { data = d; next = null ; } } // Function to insert a node at // the beginning of the singly // Linked List public void push( int new_data) { Node new_node = new Node(new_data); new_node.next = head; head = new_node; } // Function to delete a node in a // singly Linked List. void deleteNode(Node node) { // copy the next node's value in current node node.data = node.next.data; // connect the node with node's next's next node.next = node.next.next; } // Function to delete // all the nodes from // linked list containing // even numbers. void deleteEvenNodes() { Node ptr = head; Node prev = null ; //mark the current head with ptr pointer while (ptr!= null && ptr.next != null ) { // traverse the linked list before the last element if (ptr.data % 2 == 0) deleteNode(ptr); // delete the node if the value of the node is even else { prev = ptr; ptr = ptr.next; } // move the pointer to the next element and store the previous pointer } if (ptr==head && ptr.data % 2 == 0) head = null ; else if (ptr.data % 2 == 0) prev.next = null ; } // This function prints contents of linked // list starting from the given node public void printList() { Node ptr = head; while (ptr != null ) { Console.Write(ptr.data + "-> " ); ptr = ptr.next; } } // Driver code public static void Main(String []args) { List head = new List(); head.push(2); head.push(6); head.push(15); head.push(16); head.push(18); Console.Write( "\nInitial List: " ); head.printList(); head.deleteEvenNodes(); Console.Write( "\nFinal List: " ); head.printList(); } } // This code contributed by Abhijeet Kumar(abhijeet19403) |
Javascript
<script> // javascript implementation to delete all // even nodes from the singly linked list // head of list var head; // Linked list Node class Node { constructor(val) { this .data = val; this .next = null ; } } // Function to insert a node at // the beginning of the singly // Linked List function push(new_data) { var new_node = new Node(new_data); new_node.next = head; head = new_node; } // Function to delete a node in a // singly Linked List. void deleteNode(Node node) { // copy the next node's value in current node node.data = node.next.data; // connect the node with node's next's next node.next = node.next.next; } // Function to delete all the nodes // from linked list containing // even numbers. function deleteEvenNodes() { var ptr = head,prev = null ; //mark the current head with ptr pointer while (ptr!= null && ptr.next != null ) { // traverse the linked list before the last element if (ptr.data % 2 == 0) deleteNode(ptr); // delete the node if the value of the node is even else { prev = ptr; ptr = ptr.next; } // move the pointer to the next element and store the previous pointer } if (ptr==head && ptr.data % 2 == 0) head = null ; else if (ptr.data % 2 == 0) prev.next = null ; } // This function prints contents of linked // list starting from the given node function printList() { var ptr = head; while (ptr != null ) { document.write(ptr.data + "-> " ); ptr = ptr.next; } } // Driver code push(2); push(6); push(15); push(16); push(18); document.write( "<br/>Initial List: " ); printList(); deleteEvenNodes(); document.write( "<br/>Final List: " ); printList(); // This code contributed by Abhijeet Kumar(abhijeet19403) </script> |
Initial List: 18 -> 16 -> 15 -> 6 -> 2 -> Final List: 15 ->
Time Complexity: O(N)
As we are visiting every node and deleting odd valued node which is O(1) operation.
Auxiliary Space: O(1)
As constant extra space is used.
Recursive Approach:
- Base Case: If the current node is NULL, return NULL.
- If the head is null, then return null as the list is empty.
- If the head’s value is even, then return the next node recursively.
- If the head’s value is odd, then assign the head’s next to the result of the recursive call on the next node.
- Return the head.
Below is the implementation of the above approach:
C++
#include <iostream> using namespace std; // Node of the singly linked list struct Node { int data; struct Node* next; }; // Function to insert a node at the beginning of the singly linked list 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; } // Recursive function to delete all even nodes from a singly linked list void deleteEvenNodes( struct Node** head_ref) { if (*head_ref == NULL) { return ; } if ((*head_ref)->data % 2 == 0) { // If the current node is even, delete it and recursively call the function on the next node struct Node* temp = *head_ref; *head_ref = (*head_ref)->next; delete (temp); deleteEvenNodes(head_ref); } else { // If the current node is odd, recursively call the function on the next node deleteEvenNodes(&((*head_ref)->next)); } } // Function to print the singly linked list void printList( struct Node* node) { while (node != NULL) { cout << node->data << " -> " ; node = node->next; } cout << "NULL" << endl; } // Driver code int main() { // Start with the empty list Node* head = NULL; // Insert elements into the singly linked list push(&head, 2); push(&head, 6); push(&head, 15); push(&head, 16); push(&head, 18); cout << "Initial List: " ; printList(head); // Delete all even nodes from the singly linked list deleteEvenNodes(&head); cout << "Final List: " ; printList(head); return 0; } |
Java
// Java code for the above approach public class GFG { // Node of the singly linked list static class Node { int data; Node next; Node( int data) { this .data = data; this .next = null ; } } // Function to insert a node at the beginning of the // singly linked list static Node push(Node head, int new_data) { Node new_node = new Node(new_data); new_node.next = head; return new_node; } // Recursive function to delete all even nodes from a // singly linked list static Node deleteEvenNodes(Node head) { Node temp = head; Node prev = null ; // Iterate through the list while (temp != null && temp.data % 2 == 0 ) { head = temp.next; temp = head; } // Iterate further to check for even elements and // delete them while (temp != null ) { while (temp != null && temp.data % 2 != 0 ) { prev = temp; temp = temp.next; } if (temp == null ) { return head; } prev.next = temp.next; temp = prev.next; } return head; } // Function to print the singly linked list static void printList(Node node) { while (node != null ) { System.out.print(node.data + " -> " ); node = node.next; } System.out.println( "NULL" ); } public static void main(String[] args) { // Start with the empty list Node head = null ; // Insert elements into the singly linked list head = push(head, 2 ); head = push(head, 6 ); head = push(head, 15 ); head = push(head, 16 ); head = push(head, 18 ); System.out.print( "Initial List: " ); printList(head); // Delete all even nodes from the singly linked list head = deleteEvenNodes(head); System.out.print( "Final List: " ); printList(head); } } // This code is contributed by Susobhan Akhuli |
Python3
# Node of the singly linked list class Node: def __init__( self , data): self .data = data self . next = None # Function to insert a node at the beginning of the singly linked list def push(head_ref, new_data): new_node = Node(new_data) new_node. next = head_ref head_ref = new_node return head_ref # Recursive function to delete all even nodes from a singly linked list def deleteEvenNodes(head_ref): if head_ref is None : return None if head_ref.data % 2 = = 0 : # If the current node is even, delete it and recursively call the function on the next node temp = head_ref head_ref = head_ref. next del temp head_ref = deleteEvenNodes(head_ref) else : # If the current node is odd, recursively call the function on the next node head_ref. next = deleteEvenNodes(head_ref. next ) return head_ref # Function to print the singly linked list def printList(node): while node is not None : print (node.data, end = " -> " ) node = node. next print ( "NULL" ) # Driver code if __name__ = = "__main__" : # Start with an empty list head = None # Insert elements into the singly linked list head = push(head, 2 ) head = push(head, 6 ) head = push(head, 15 ) head = push(head, 16 ) head = push(head, 18 ) print ( "Initial List: " , end = "") printList(head) # Delete all even nodes from the singly linked list head = deleteEvenNodes(head) print ( "Final List: " , end = "") printList(head) |
C#
// C# code for the above approach using System; // Node of the singly linked list public class Node { public int data; public Node next; // Constructor to initialize a new node public Node( int data) { this .data = data; this .next = null ; } } public class LinkedList { // Function to insert a node at the beginning of the // singly linked list public static void Push( ref Node headRef, int newData) { Node newNode = new Node(newData); newNode.next = headRef; headRef = newNode; } // Recursive function to delete all even nodes from a // singly linked list public static void DeleteEvenNodes( ref Node headRef) { if (headRef == null ) { return ; } if (headRef.data % 2 == 0) { // If the current node is even, delete it and // recursively call the function on the next // node _ = headRef; headRef = headRef.next; _ = null ; DeleteEvenNodes( ref headRef); } else { // If the current node is odd, recursively call // the function on the next node DeleteEvenNodes( ref headRef.next); } } // Function to print the singly linked list public static void PrintList(Node node) { while (node != null ) { Console.Write(node.data + " -> " ); node = node.next; } Console.WriteLine( "NULL" ); } // Driver code public static void Main( string [] args) { // Start with the empty list Node head = null ; // Insert elements into the singly linked list Push( ref head, 2); Push( ref head, 6); Push( ref head, 15); Push( ref head, 16); Push( ref head, 18); Console.Write( "Initial List: " ); PrintList(head); // Delete all even nodes from the singly linked list DeleteEvenNodes( ref head); Console.Write( "Final List: " ); PrintList(head); } } // This code is contributed by Susobhan Akhuli |
Javascript
// Node of the singly linked list class Node { constructor(data) { this .data = data; this .next = null ; } } // Function to insert a node at the beginning of the singly linked list function push(head, new_data) { let new_node = new Node(new_data); new_node.next = head; return new_node; } // Recursive function to delete all even nodes from a singly linked list function deleteEvenNodes(head) { if (head === null ) { return null ; } if (head.data % 2 === 0) { // If the current node is even, delete it and recursively call the function on the next node let temp = head.next; delete head; return deleteEvenNodes(temp); } else { // If the current node is odd, recursively call the function on the next node head.next = deleteEvenNodes(head.next); return head; } } // Function to print the singly linked list function printList(node) { while (node !== null ) { console.log(node.data + " -> " ); node = node.next; } console.log( "NULL" ); } // Driver code function main() { // Start with an empty list let head = null ; // Insert elements into the singly linked list head = push(head, 2); head = push(head, 6); head = push(head, 15); head = push(head, 16); head = push(head, 18); console.log( "Initial List: " ); printList(head); // Delete all even nodes from the singly linked list head = deleteEvenNodes(head); console.log( "Final List: " ); printList(head); } main(); |
Output:
Initial List: 18 -> 16 -> 15 -> 6 -> 2 -> NULL
Final List: 15 -> NULL
Time Complexity: O(n), where n is the number of nodes in the linked list.
Space Complexity: O(n), This is because the function creates n recursive function calls on the call stack, one for each node in the linked list.