Given a circular singly linked list containing N nodes, the task is to delete all the even nodes from the list.
Examples:
Input : 57->11->2->56->12->61 Output : List after deletion : 57 -> 11 -> 61 Input : 9->11->32->6->13->20 Output : List after deletion : 9 -> 11 -> 13
The idea is to traverse the nodes of the circular 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++
// CPP program to delete all even // node from a Circular singly linked list #include <bits/stdc++.h> using namespace std;
// Structure for a node struct Node {
int data;
struct Node* next;
}; // Function to insert a node at the beginning // of a Circular linked list void push( struct Node** head_ref, int data)
{ struct Node* ptr1 = ( struct Node*) malloc ( sizeof ( struct Node));
struct Node* temp = *head_ref;
ptr1->data = data;
ptr1->next = *head_ref;
// If linked list is not NULL then
// set the next of last node
if (*head_ref != NULL) {
while (temp->next != *head_ref)
temp = temp->next;
temp->next = ptr1;
}
else
ptr1->next = ptr1; // For the first node
*head_ref = ptr1;
} // Delete the node if it is even void deleteNode(Node* head_ref, Node* del)
{ struct Node* temp = head_ref;
// If node to be deleted is head node
if (head_ref == del)
head_ref = del->next;
// traverse list till not found
// delete node
while (temp->next != del) {
temp = temp->next;
}
// copy address of node
temp->next = del->next;
// Finally, free the memory occupied by del
free (del);
return ;
} // Function to delete all even nodes // from the singly circular linked list void deleteEvenNodes(Node* head)
{ struct Node* ptr = head;
struct Node* next;
// traverse list till the end
// if the node is even then delete it
do {
// point to next node
next = ptr->next;
// if node is even
if (ptr->data % 2 == 0)
deleteNode(head, ptr);
// get the next node to process
ptr = next;
} while (ptr != head);
} // Function to print nodes void printList( struct Node* head)
{ struct Node* temp = head;
if (head != NULL) {
do {
printf ( "%d " , temp->data);
temp = temp->next;
} while (temp != head);
}
} // Driver code int main()
{ // Initialize lists as empty
struct Node* head = NULL;
// Created linked list will be 57->11->2->56->12->61
push(&head, 61);
push(&head, 12);
push(&head, 56);
push(&head, 2);
push(&head, 11);
push(&head, 57);
cout << "\nList after deletion : " ;
deleteEvenNodes(head);
printList(head);
return 0;
} |
Java
// Java program to delete all prime // node from a Circular singly linked list class GFG
{ // Structure for a node static class Node
{ int data;
Node next;
}; // Function to insert a node at the beginning // of a Circular linked list static Node push(Node head_ref, int data)
{ Node ptr1 = new Node();
Node temp = head_ref;
ptr1.data = data;
ptr1.next = head_ref;
// If linked list is not null then
// set the next of last node
if (head_ref != null )
{
while (temp.next != head_ref)
temp = temp.next;
temp.next = ptr1;
return head_ref;
}
else
ptr1.next = ptr1; // For the first node
head_ref = ptr1;
return head_ref;
} // Delete the node if it is even static Node deleteNode(Node head_ref, Node del)
{ Node temp = head_ref;
// If node to be deleted is head node
if (head_ref == del)
head_ref = del.next;
// traverse list till not found
// delete node
while (temp.next != del)
{
temp = temp.next;
}
// copy address of node
temp.next = del.next;
return head_ref;
} // Function to delete all even nodes // from the singly circular linked list static Node deleteEvenNodes(Node head)
{ Node ptr = head;
Node next;
// traverse list till the end
// if the node is even then delete it
do
{
// if node is even
if (ptr.data % 2 == 0 )
deleteNode(head, ptr);
// point to next node
next = ptr.next;
ptr = next;
}
while (ptr != head);
return head;
} // Function to print nodes static void printList(Node head)
{ Node temp = head;
if (head != null )
{
do
{
System.out.printf( "%d " , temp.data);
temp = temp.next;
}
while (temp != head);
}
} // Driver code public static void main(String args[])
{ // Initialize lists as empty
Node head = null ;
// Created linked list will be 57.11.2.56.12.61
head=push(head, 61 );
head=push(head, 12 );
head=push(head, 56 );
head=push(head, 2 );
head=push(head, 11 );
head=push(head, 57 );
System.out.println( "\nList after deletion : " );
head=deleteEvenNodes(head);
printList(head);
} } // This code is contributed by Arnab Kundu |
Python3
# Python3 program to delete all even # node from a Circular singly linked list import math
# Structure for a node class Node:
def __init__( self , data):
self .data = data
self . next = None
# Function to insert a node at the beginning # of a Circular linked list def push(head_ref, data):
ptr1 = Node(data)
temp = head_ref
ptr1.data = data
ptr1. next = head_ref
# If linked list is not None then
# set the next of last node
if (head_ref ! = None ):
while (temp. next ! = head_ref):
temp = temp. next
temp. next = ptr1
else :
ptr1. next = ptr1 # For the first node
head_ref = ptr1
return head_ref
# Delete the node if it is even def deleteNode(head_ref, delete):
temp = head_ref
# If node to be deleted is head node
if (head_ref = = delete):
head_ref = delete. next
# traverse list till not found
# delete node
while (temp. next ! = delete):
temp = temp. next
# copy address of node
temp. next = delete. next
# Finally, free the memory occupied by delete
# Function to delete all even nodes # from the singly circular linked list def deleteEvenNodes(head):
ptr = head
next = None
# traverse list till the end
# if the node is even then delete it
# if node is even
next = ptr. next
ptr = next
while (ptr ! = head):
if (ptr.data % 2 = = 0 ):
deleteNode(head, ptr)
# point to next node
next = ptr. next
ptr = next
return head
# Function to print nodes def printList(head):
temp = head
if (head ! = None ):
print (temp.data, end = " " )
temp = temp. next
while (temp ! = head):
print (temp.data, end = " " )
temp = temp. next
# Driver code if __name__ = = '__main__' :
# Initialize lists as empty
head = None
# Created linked list will be 57.11.2.56.12.61
head = push(head, 61 )
head = push(head, 12 )
head = push(head, 56 )
head = push(head, 2 )
head = push(head, 11 )
head = push(head, 57 )
print ( "List after deletion : " , end = "")
head = deleteEvenNodes(head)
printList(head)
# This code is contributed by Srathore |
C#
// C# program to delete all prime // node from a Circular singly linked list using System;
class GFG
{ // Structure for a node public class Node
{ public int data;
public Node next;
}; // Function to insert a node at the beginning // of a Circular linked list static Node push(Node head_ref, int data)
{ Node ptr1 = new Node();
Node temp = head_ref;
ptr1.data = data;
ptr1.next = head_ref;
// If linked list is not null then
// set the next of last node
if (head_ref != null )
{
while (temp.next != head_ref)
temp = temp.next;
temp.next = ptr1;
return head_ref;
}
else
ptr1.next = ptr1; // For the first node
head_ref = ptr1;
return head_ref;
} // Delete the node if it is even static Node deleteNode(Node head_ref, Node del)
{ Node temp = head_ref;
// If node to be deleted is head node
if (head_ref == del)
head_ref = del.next;
// traverse list till not found
// delete node
while (temp.next != del)
{
temp = temp.next;
}
// copy address of node
temp.next = del.next;
return head_ref;
} // Function to delete all even nodes // from the singly circular linked list static Node deleteEvenNodes(Node head)
{ Node ptr = head;
Node next;
// traverse list till the end
// if the node is even then delete it
do
{
// if node is even
if (ptr.data % 2 == 0)
deleteNode(head, ptr);
// point to next node
next = ptr.next;
ptr = next;
}
while (ptr != head);
return head;
} // Function to print nodes static void printList(Node head)
{ Node temp = head;
if (head != null )
{
do
{
Console.Write( "{0} " , temp.data);
temp = temp.next;
}
while (temp != head);
}
} // Driver code public static void Main(String []args)
{ // Initialize lists as empty
Node head = null ;
// Created linked list will be 57.11.2.56.12.61
head=push(head, 61);
head=push(head, 12);
head=push(head, 56);
head=push(head, 2);
head=push(head, 11);
head=push(head, 57);
Console.WriteLine( "\nList after deletion : " );
head=deleteEvenNodes(head);
printList(head);
} } // This code has been contributed by 29AjayKumar |
Javascript
<script> // javascript program to delete all prime // node from a Circular singly linked list // Structure for a node class Node { constructor() {
this .data = 0;
this .next = null ;
}
} // Function to insert a node at the beginning
// of a Circular linked list
function push(head_ref , data) {
var ptr1 = new Node();
var temp = head_ref;
ptr1.data = data;
ptr1.next = head_ref;
// If linked list is not null then
// set the next of last node
if (head_ref != null ) {
while (temp.next != head_ref)
temp = temp.next;
temp.next = ptr1;
return head_ref;
} else
ptr1.next = ptr1; // For the first node
head_ref = ptr1;
return head_ref;
}
// Delete the node if it is even
function deleteNode(head_ref, del) {
var temp = head_ref;
// If node to be deleted is head node
if (head_ref == del)
head_ref = del.next;
// traverse list till not found
// delete node
while (temp.next != del) {
temp = temp.next;
}
// copy address of node
temp.next = del.next;
return head_ref;
}
// Function to delete all even nodes
// from the singly circular linked list
function deleteEvenNodes(head) {
var ptr = head;
var next;
// traverse list till the end
// if the node is even then delete it
do {
// if node is even
if (ptr.data % 2 == 0)
deleteNode(head, ptr);
// point to next node
next = ptr.next;
ptr = next;
} while (ptr != head);
return head;
}
// Function to print nodes
function printList(head) {
var temp = head;
if (head != null ) {
do {
document.write( temp.data+ " " );
temp = temp.next;
} while (temp != head);
}
}
// Driver code
// Initialize lists as empty
var head = null ;
// Created linked list will be 57.11.2.56.12.61
head = push(head, 61);
head = push(head, 12);
head = push(head, 56);
head = push(head, 2);
head = push(head, 11);
head = push(head, 57);
document.write( "\nList after deletion : " );
head = deleteEvenNodes(head);
printList(head);
// This code contributed by umadevi9616 </script> |
Output
List after deletion : 57 11 61
Complexity Analysis:
-
Time Complexity: O(N^2)
- As to delete each node we need O(N) time and we have to process every node.
-
Auxiliary Space: O(1)
- As constant extra space is used