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 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 ptr1->next = ptr1; // For the first node *head_ref = ptr1;}// Delete the node if it is evenvoid 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 listvoid 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 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 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 listimport math# Structure for a nodeclass Node: def __init__(self, data): self.data = data self.next = None# Function to insert a node at the beginning# of a Circular linked listdef 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 evendef 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 listdef 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 nodesdef 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 codeif __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 nodeclass 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 emptyvar 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
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