Prerequisite: Delete all the even nodes of a Circular Linked List
Given a circular singly linked list containing N nodes, the task is to delete all the odd nodes from the list.
Examples:
Input: 572->112->21->5->1->6
Output: 572 -> 112 -> 6
Explanation: All the odd valued nodes have been deleted
Input: 9->11->32->6->13->20
Output: 32 -> 6 -> 20
Approach:
The idea is to traverse the nodes of the circular singly linked list one by one and get the pointer of the nodes having odd data. Delete those nodes by following the approach used in this post.
Below is the implementation of the above idea:
C++
// C++ program to delete all odd// node from a Circular singly linked list#include <bits/stdc++.h>using namespace std;// Structure for a nodestruct Node { int data; struct Node* next;};// Function to insert a node at the beginning// of a Circular linked listvoid 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 // For the first node ptr1->next = ptr1; *head_ref = ptr1;}// Delete the node if it is oddvoid 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 odd nodes// from the singly circular linked listvoid deleteoddNodes(Node* head){ struct Node* ptr = head; struct Node* next; // Traverse list till the end // if the node is odd then delete it do { // point to next node next = ptr->next; // if node is odd if ((ptr->data % 2) == 1) deleteNode(head, ptr); // get the next element ptr = next; } while (ptr != head);}// Function to print nodesvoid printList(struct Node* head){ struct Node* temp = head; if (head != NULL) { do { printf("%d ", temp->data); temp = temp->next; } while (temp != head); }}// Driver codeint main(){ // Initialize lists as empty struct Node* head = NULL; // Created linked list will be 56->61->57->11->12->2 push(&head, 2); push(&head, 12); push(&head, 11); push(&head, 57); push(&head, 61); push(&head, 56); cout << "\nList after deletion : "; deleteoddNodes(head); printList(head); return 0;} |
Java
// Java program to delete all prime// node from a Circular singly linked listclass 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// For the first node ptr1.next = ptr1; head_ref = ptr1; return head_ref; } // Delete the node if it is odd 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 odd nodes // from the singly circular linked list static Node deleteoddNodes(Node head) { Node ptr = head; Node next; // Traverse list till the end // if the node is odd then delete it do { // If node is odd if (ptr.data % 2 == 1) 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 56->61->57->11->12->2 head = push(head, 2); head = push(head, 12); head = push(head, 11); head = push(head, 57); head = push(head, 61); head = push(head, 56); System.out.println("\nList after deletion : "); head = deleteoddNodes(head); printList(head); }} |
Python
# Python3 program to delete all odd # 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 odd 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 # Function to delete all odd nodes # from the singly circular linked list def deleteoddNodes(head): ptr = head next = None # Traverse list till the end # if the node is odd then delete it # if node is odd next = ptr.next ptr = next while (ptr != head): if (ptr.data % 2 == 1): 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 56->61->57->11->12->2 head = push(head, 2) head = push(head, 12) head = push(head, 11) head = push(head, 57) head = push(head, 61) head = push(head, 56) print("List after deletion : ", end = "") head = deleteoddNodes(head) printList(head) |
C#
// C# program to delete all prime// node from a Circular singly linked listusing 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 // For the first node ptr1.next = ptr1; head_ref = ptr1; return head_ref; } // Delete the node if it is odd 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 odd nodes // from the singly circular linked list static Node deleteoddNodes(Node head) { Node ptr = head; Node next; // Traverse list till the end // if the node is odd then delete it do { // If node is odd if (ptr.data % 2 == 1) 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 56->61->57->11->12->2 head = push(head, 2); head = push(head, 12); head = push(head, 11); head = push(head, 57); head = push(head, 61); head = push(head, 56); Console.WriteLine("\nList after deletion : "); head = deleteoddNodes(head); printList(head); }} |
Javascript
<script>// JavaScript program to delete all prime// node from a Circular singly linked list// Structure for a nodeclass Node { constructor() { this.data = 0; this.next = null; }};// Function to insert a node at the beginning// of a Circular linked listfunction 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 // For the first node ptr1.next = ptr1; head_ref = ptr1; return head_ref;}// Delete the node if it is oddfunction 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 odd nodes// from the singly circular linked listfunction deleteoddNodes(head){ var ptr = head; var next; // Traverse list till the end // if the node is odd then delete it do { // If node is odd if (ptr.data % 2 == 1) deleteNode(head, ptr); // Point to next node next = ptr.next; ptr = next; } while (ptr != head); return head;}// Function to print nodesfunction printList(head){ var temp = head; if (head != null) { do { document.write(temp.data+ " "); temp = temp.next; } while (temp != head); }}// Driver code// Initialize lists as emptyvar head = null;// Created linked list will be 56->61->57->11->12->2head = push(head, 2);head = push(head, 12);head = push(head, 11);head = push(head, 57);head = push(head, 61);head = push(head, 56);document.write("List after deletion : ");head = deleteoddNodes(head);printList(head);</script> |
Output:
List after deletion : 56 12 2
Time Complexity: O(N^2)
As deleteNode function takes O(N) time and we have to process every element in worst case
Auxiliary Space: O(1)
As constant extra space is used
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