Given a doubly linked list containing N nodes and a number X, the task is to delete all the nodes from the list that are greater than the given value X.
Examples:
Input: 10 8 4 11 9, X = 9
Output: 8 4 9
Explanation: 10 and 11 are greater than 9. So after removing them doubly linked list will become 8 4 9.Input: 4 4 2 1 3 5, X = 2
Output: 2 1
Approach: Traverse the nodes of the doubly linked list one by one and get the pointer of the nodes having data value greater than x. Delete these nodes by following the approach used in this post.
Implementation:
C++
// C++ implementation to delete all// the nodes from the doubly// linked list that are greater than// the specified value x#include <bits/stdc++.h>using namespace std;// Node of the doubly linked liststruct Node { int data; Node *prev, *next;};// function to insert a node at the beginning// of the Doubly Linked Listvoid push(Node** head_ref, int new_data){ // allocate node Node* new_node = new Node(); // put in the data new_node->data = new_data; // since we are adding at the beginning, // prev is always NULL new_node->prev = NULL; // link the old list of the new node new_node->next = (*head_ref); // change prev of head node to new node if ((*head_ref) != NULL) (*head_ref)->prev = new_node; // move the head to point to the new node (*head_ref) = new_node;}// function to delete a node in a Doubly Linked List.// head_ref --> pointer to head node pointer.// del --> pointer to node to be deletedvoid deleteNode(Node** head_ref, Node* del){ // base case if (*head_ref == NULL || del == NULL) return; // If node to be deleted is head node if (*head_ref == del) *head_ref = del->next; // Change next only if node to be // deleted is NOT the last node if (del->next != NULL) del->next->prev = del->prev; // Change prev only if node to be // deleted is NOT the first node if (del->prev != NULL) del->prev->next = del->next; // Finally, free the memory occupied by del free(del); return;}// function to delete all the nodes// from the doubly linked// list that are greater than the// specified value xvoid deleteGreaterNodes(Node** head_ref, int x){ Node* ptr = *head_ref; Node* next; while (ptr != NULL) { next = ptr->next; // if true, delete node 'ptr' if (ptr->data > x) deleteNode(head_ref, ptr); ptr = next; }}// function to print nodes in a// given doubly linked listvoid printList(Node* head){ while (head != NULL) { cout << head->data << " "; head = head->next; }}// Driver program to test aboveint main(){ // start with the empty list Node* head = NULL; // create the doubly linked list // 10<->8<->4<->11<->9 push(&head, 9); push(&head, 11); push(&head, 4); push(&head, 8); push(&head, 10); int x = 9; cout << "Original List: "; printList(head); deleteGreaterNodes(&head, x); cout << "\nModified List: "; printList(head);} |
Java
// Java implementation to delete all // the nodes from the doubly // linked list that are greater than // the specified value x class GFG{// Node of the doubly linked list static class Node { int data; Node prev, next; }; // function to insert a node at the beginning // of the Doubly Linked List static Node push(Node head_ref, int new_data) { // allocate node Node new_node = new Node(); // put in the data new_node.data = new_data; // since we are adding at the beginning, // prev is always null new_node.prev = null; // link the old list of the new node new_node.next = (head_ref); // change prev of head node to new node if ((head_ref) != null) (head_ref).prev = new_node; // move the head to point to the new node (head_ref) = new_node; return head_ref;} // function to delete a node in a Doubly Linked List. // head_ref -. pointer to head node pointer. // del -. pointer to node to be deleted static Node deleteNode(Node head_ref, Node del) { // base case if (head_ref == null || del == null) return null; // If node to be deleted is head node if (head_ref == del) head_ref = del.next; // Change next only if node to be // deleted is NOT the last node if (del.next != null) del.next.prev = del.prev; // Change prev only if node to be // deleted is NOT the first node if (del.prev != null) del.prev.next = del.next; return head_ref; } // function to delete all the nodes // from the doubly linked // list that are greater than the // specified value x static Node deleteGreaterNodes(Node head_ref, int x) { Node ptr = head_ref; Node next; while (ptr != null) { next = ptr.next; // if true, delete node 'ptr' if (ptr.data > x) deleteNode(head_ref, ptr); ptr = next; } return head_ref;} // function to print nodes in a // given doubly linked list static void printList(Node head) { while (head != null) { System.out.print( head.data + " "); head = head.next; } } // Driver code public static void main(String args[]){ // start with the empty list Node head = null; // create the doubly linked list // 10<.8<.4<.11<.9 head = push(head, 9); head = push(head, 11); head = push(head, 4); head = push(head, 8); head = push(head, 10); int x = 9; System.out.print( "Original List: "); printList(head); head=deleteGreaterNodes(head, x); System.out.print( "\nModified List: "); printList(head); } }// This code is contributed by Arnab Kundu |
Python3
# Python3 implementation to delete all# the nodes from the doubly# linked list that are greater than# the specified value x# Link list node class Node: def __init__(self, data): self.data = data self.next = None self.prev = None # function to insert a node at the beginning # of the Doubly Linked List def push( head_ref, new_data): # allocate node new_node = Node(0) # put in the data new_node.data = new_data # since we are adding at the beginning, # prev is always None new_node.prev = None # link the old list of the new node new_node.next = (head_ref) # change prev of head node to new node if ((head_ref) != None) : (head_ref).prev = new_node # move the head to point to the new node (head_ref) = new_node return head_ref# function to delete a node in a Doubly Linked List. # head_ref -. pointer to head node pointer. # del -. pointer to node to be deleted def deleteNode(head_ref, del_) : # base case if (head_ref == None or del_ == None) : return head_ref # If node to be deleted is head node if (head_ref == del_) : head_ref = del_.next # Change next only if node to be # deleted is NOT the last node if (del_.next != None) : del_.next.prev = del_.prev # Change prev only if node to be # deleted is NOT the first node if (del_.prev != None) : del_.prev.next = del_.next return head_ref# function to delete all the nodes # from the doubly linked # list that are greater than the # specified value x def deleteGreaterNodes(head_ref, x) : ptr = head_ref next = None while (ptr != None) : next = ptr.next # if true, delete node 'ptr' if (ptr.data > x) : head_ref = deleteNode(head_ref, ptr) ptr = next return head_ref# function to print nodes in a # given doubly linked list def printList( head) : while (head != None) : print( head.data, end= " ") head = head.next# Driver program to test above # start with the empty list head = None# create the doubly linked list # 10<.8<.4<.11<.9 head = push(head, 9) head = push(head, 11) head = push(head, 4) head = push(head, 8) head = push(head, 10) x = 9print("Original List: ") printList(head) head = deleteGreaterNodes(head, x) print("\nModified List: ") printList(head) # This code is contributed by Arnab Kundu |
C#
// C# implementation to delete all // the nodes from the doubly // linked list that are greater than // the specified value xusing System;class GFG{ // Node of the doubly linked list public class Node { public int data; public Node prev, next; }; // function to insert a node at the beginning // of the Doubly Linked List static Node push(Node head_ref, int new_data) { // allocate node Node new_node = new Node(); // put in the data new_node.data = new_data; // since we are adding at the beginning, // prev is always null new_node.prev = null; // link the old list of the new node new_node.next = (head_ref); // change prev of head node to new node if ((head_ref) != null) (head_ref).prev = new_node; // move the head to point to the new node (head_ref) = new_node; return head_ref;} // function to delete a node in a Doubly Linked List. // head_ref -. pointer to head node pointer. // del -. pointer to node to be deleted static Node deleteNode(Node head_ref, Node del) { // base case if (head_ref == null || del == null) return null; // If node to be deleted is head node if (head_ref == del) head_ref = del.next; // Change next only if node to be // deleted is NOT the last node if (del.next != null) del.next.prev = del.prev; // Change prev only if node to be // deleted is NOT the first node if (del.prev != null) del.prev.next = del.next; return head_ref; } // function to delete all the nodes // from the doubly linked // list that are greater than the // specified value x static Node deleteGreaterNodes(Node head_ref, int x) { Node ptr = head_ref; Node next; while (ptr != null) { next = ptr.next; // if true, delete node 'ptr' if (ptr.data > x) deleteNode(head_ref, ptr); ptr = next; } return head_ref;} // function to print nodes in a // given doubly linked list static void printList(Node head) { while (head != null) { Console.Write( head.data + " "); head = head.next; } } // Driver code public static void Main(String []args){ // start with the empty list Node head = null; // create the doubly linked list // 10<.8<.4<.11<.9 head = push(head, 9); head = push(head, 11); head = push(head, 4); head = push(head, 8); head = push(head, 10); int x = 9; Console.Write( "Original List: "); printList(head); head=deleteGreaterNodes(head, x); Console.Write( "\nModified List: "); printList(head); } }// This code contributed by Rajput-Ji |
Javascript
<script>// Javascript implementation to delete all// the nodes from the doubly// linked list that are greater than// the specified value x// Node of the doubly linked listclass Node{ constructor() { this.prev = null; this.next = null; this.data = 0; }}// function to insert a node at the beginning// of the Doubly Linked Listfunction push(head_ref,new_data){ // allocate node let new_node = new Node(); // put in the data new_node.data = new_data; // since we are adding at the beginning, // prev is always null new_node.prev = null; // link the old list of the new node new_node.next = (head_ref); // change prev of head node to new node if ((head_ref) != null) (head_ref).prev = new_node; // move the head to point to the new node (head_ref) = new_node; return head_ref;}// function to delete a node in a Doubly Linked List.// head_ref -. pointer to head node pointer.// del -. pointer to node to be deletedfunction deleteNode(head_ref,del){ // base case if (head_ref == null || del == null) return null; // If node to be deleted is head node if (head_ref == del) head_ref = del.next; // Change next only if node to be // deleted is NOT the last node if (del.next != null) del.next.prev = del.prev; // Change prev only if node to be // deleted is NOT the first node if (del.prev != null) del.prev.next = del.next; return head_ref;}// function to delete all the nodes// from the doubly linked// list that are greater than the// specified value xfunction deleteGreaterNodes(head_ref,x){ let ptr = head_ref; let next; while (ptr != null) { next = ptr.next; // if true, delete node 'ptr' if (ptr.data > x) deleteNode(head_ref, ptr); ptr = next; } return head_ref;}// function to print nodes in a// given doubly linked listfunction printList(head){ while (head != null) { document.write( head.data + " "); head = head.next; }}// Driver code// start with the empty listlet head = null;// create the doubly linked list// 10<.8<.4<.11<.9head = push(head, 9);head = push(head, 11);head = push(head, 4);head = push(head, 8);head = push(head, 10);let x = 9;document.write( "Original List: ");printList(head);head=deleteGreaterNodes(head, x);document.write( "<br>Modified List: ");printList(head);// This code is contributed by avanitrachhadiya2155</script> |
Output
Original List: 10 8 4 11 9 Modified List: 8 4 9
complexity Analysis:
- Time Complexity: O(N)
- Auxiliary Space: O(1)
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