Given a doubly-linked list containing N nodes, the task is to delete all nodes from the list which are divisible by K.
Examples:
Input: List = 15 <=> 16 <=> 6 <=> 7 <=> 17, K = 2
Output: Final List = 15 <=> 7 <=> 17Input: List = 5 <=> 3 <=> 4 <=> 2 <=> 9, K = 3
Output: Final List = 5 <=> 4 <=> 2
Approach: The idea is to traverse the nodes of the doubly linked list one by one and get the pointer of the nodes which are divisible by K. 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 // from the doubly linked list which // are divisible by K #include <bits/stdc++.h> using namespace std;
// Node of the doubly linked list struct Node {
int data;
Node *prev, *next;
}; // function to insert a node at the beginning // of the Doubly Linked List void push(Node** head_ref, int new_data)
{ // allocate node
Node* new_node = (Node*) malloc ( sizeof ( struct 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 deleted void 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 nodes from the // doubly linked list divisible by K void deleteDivisibleNodes(Node** head_ref, int K)
{ Node* ptr = *head_ref;
Node* next;
while (ptr != NULL) {
next = ptr->next;
// if true, delete node 'ptr'
if (ptr->data % K == 0)
deleteNode(head_ref, ptr);
ptr = next;
}
} // function to print nodes in a // given doubly linked list void printList(Node* head)
{ while (head != NULL) {
cout << head->data << " " ;
head = head->next;
}
} // Driver program int main()
{ // start with the empty list
Node* head = NULL;
// create the doubly linked list
// 15 <-> 16 <-> 7 <-> 6 <-> 17
push(&head, 17);
push(&head, 6);
push(&head, 7);
push(&head, 16);
push(&head, 15);
int K = 2;
cout << "Original List: " ;
printList(head);
deleteDivisibleNodes(&head, K);
cout << "\nModified List: " ;
printList(head);
} |
Java
// Java implementation to delete all // from the doubly linked list which // are divisible by K 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 nodes from the // doubly linked list divisible by K static Node deleteDivisibleNodes(Node head_ref, int K)
{ Node ptr = head_ref;
Node next;
while (ptr != null )
{
next = ptr.next;
// if true, delete node 'ptr'
if (ptr.data % K == 0 )
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
// 15 <. 16 <. 7 <. 6 <. 17
head = push(head, 17 );
head = push(head, 6 );
head = push(head, 7 );
head = push(head, 16 );
head = push(head, 15 );
int K = 2 ;
System.out.print( "Original List: " );
printList(head);
head=deleteDivisibleNodes(head, K);
System.out.print( "\nModified List: " );
printList(head);
} } // This code is contributed by Arnab Kundu |
Python3
# Python3 implementation to delete all
# from the doubly linked list which # are divisible by K import math
# Node of the doubly linked list class Node:
def __init__( self ,data):
self .data = data
self . next = 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(new_data)
# 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, delete):
# base case
if (head_ref = = None or delete = = None ):
return
# If node to be deleted is head node
if (head_ref = = delete):
head_ref = delete. next
# Change next only if node to be
# deleted is NOT the last node
if (delete. next ! = None ):
delete. next .prev = delete.prev
# Change prev only if node to be
# deleted is NOT the first node
if (delete.prev ! = None ):
delete.prev. next = delete. next
# Finally, free the memory
# occupied by del, free(del)
return
# function to delete all nodes from the # doubly linked list divisible by K def deleteDivisibleNodes(head_ref, K):
ptr = head_ref
#next
while (ptr ! = None ) :
next = ptr. next
# if true, delete node 'ptr'
if (ptr.data % K = = 0 ):
deleteNode(head_ref, ptr)
ptr = next
# function to print nodes in a # given doubly linked list def printList(head):
while (head ! = None ):
print (head.data, end = " " )
head = head. next
# Driver Code if __name__ = = '__main__' :
# start with the empty list
head = None
# create the doubly linked list
# 15 <- 16 <- 7 <- 6 <- 17
head = push(head, 17 )
head = push(head, 6 )
head = push(head, 7 )
head = push(head, 16 )
head = push(head, 15 )
K = 2
print ( "Original List: " , end = "")
printList(head)
deleteDivisibleNodes(head, K)
print ( "\nModified List: " , end = "")
printList(head)
# This code is contributed by AbhiThakur |
C#
// C# implementation to delete all // from the doubly linked list which // are divisible by K using 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 nodes from the // doubly linked list divisible by K static Node deleteDivisibleNodes(Node head_ref, int K)
{ Node ptr = head_ref;
Node next;
while (ptr != null )
{
next = ptr.next;
// if true, delete node 'ptr'
if (ptr.data % K == 0)
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
// 15 <. 16 <. 7 <. 6 <. 17
head = push(head, 17);
head = push(head, 6);
head = push(head, 7);
head = push(head, 16);
head = push(head, 15);
int K = 2;
Console.Write( "Original List: " );
printList(head);
head = deleteDivisibleNodes(head, K);
Console.Write( "\nModified List: " );
printList(head);
} } // This code contributed by Rajput-Ji |
Javascript
<script> // javascript implementation to delete all // from the doubly linked list which // are divisible by K // Node of the doubly linked list class Node {
constructor(val) {
this .data = val;
this .prev = null ;
this .next = null ;
}
}
// function to insert a node at the beginning
// of the Doubly Linked List
function push(head_ref , new_data) {
// allocate node
var 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
function 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 nodes from the
// doubly linked list divisible by K
function deleteDivisibleNodes(head_ref , K) {
var ptr = head_ref;
var next;
while (ptr != null ) {
next = ptr.next;
// if true, delete node 'ptr'
if (ptr.data % K == 0)
deleteNode(head_ref, ptr);
ptr = next;
}
return head_ref;
}
// function to print nodes in a
// given doubly linked list
function printList(head) {
while (head != null ) {
document.write(head.data + " " );
head = head.next;
}
}
// Driver code
// start with the empty list
var head = null ;
// create the doubly linked list
// 15 <. 16 <. 7 <. 6 <. 17
head = push(head, 17);
head = push(head, 6);
head = push(head, 7);
head = push(head, 16);
head = push(head, 15);
var K = 2;
document.write( "Original List: " );
printList(head);
head = deleteDivisibleNodes(head, K);
document.write( "<br/>Modified List: " );
printList(head);
// This code is contributed by todaysgaurav </script> |
Output
Original List: 15 16 7 6 17 Modified List: 15 7 17
Complexity Analysis:
- Time Complexity: O(N), where N is the total number of nodes.
- Space Complexity: O(1) since using constant variables