Given a doubly linked list containing N nodes, the task is to delete all nodes from the list which are prime.
Examples:
Input: List = 15 <=> 16 <=> 6 <=> 7 <=> 17
Output: Final List = 15 <=> 16 <=> 6Input: List = 5 <=> 3 <=> 4 <=> 2 <=> 9
Output: Final List = 5 <=> 4 <=> 9
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 prime. Delete those nodes by following the approach used in this post.
Below is the implementation of above idea:
C++
// C++ implementation to delete all // prime nodes from the doubly // linked list #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 check if a number is prime bool isPrime( int n) { // Corner cases if (n <= 1) return false ; if (n <= 3) return true ; // This is checked so that we can skip // middle five numbers in below loop if (n % 2 == 0 || n % 3 == 0) return false ; for ( int i = 5; i * i <= n; i = i + 6) if (n % i == 0 || n % (i + 2) == 0) return false ; return true ; } // 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 prime nodes // from the doubly linked list void deletePrimeNodes(Node** head_ref) { Node* ptr = *head_ref; Node* next; while (ptr != NULL) { next = ptr->next; // if true, delete node 'ptr' if (isPrime(ptr->data)) 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); cout << "Original List: " ; printList(head); deletePrimeNodes(&head); cout << "\nModified List: " ; printList(head); } |
Java
// Node of the doubly linked list class Node { int data; Node prev, next; Node( int value) // A constructor is called here { prev = null ; // By default previous pointer is // pointed to NULL data = value; // value is assigned to the data next = null ; // By default next pointer is pointed // to NULL } }; // Java implementation to delete all // prime nodes from the doubly // linked list class GFG { static Node head = null ; // function to insert a node at the beginning // of the Doubly Linked List static void push( int new_data) { //taking new node Node n = new Node(new_data); //setting new node at start n.next = head; //setting previous head node's previous as new node if (head != null ) { head.prev = n; } head = n; } // Function to check if a number is prime static boolean isPrime( int n) { // Corner cases if (n <= 1 ) return false ; if (n <= 3 ) return true ; // This is checked so that we can skip // middle five numbers in below loop if (n % 2 == 0 || n % 3 == 0 ) return false ; for ( int i = 5 ; i * i <= n; i = i + 6 ) if (n % i == 0 || n % (i + 2 ) == 0 ) return false ; return true ; } // 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 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; } // function to delete all prime nodes // from the doubly linked list static void deletePrimeNodes(Node head_ref) { Node ptr = head_ref; Node next; while (ptr != null ) { next = ptr.next; // if true, delete node 'ptr' if (isPrime(ptr.data)) deleteNode(head_ref, ptr); ptr = next; } } // function to print nodes in a // given doubly linked list static void printList(Node head) { Node temp = head; while (temp != null ) { System.out.print( temp.data + " " ); temp = temp.next; } } // Driver program public static void main(String args[]) { // create the doubly linked list // 15 <. 16 <. 7 <. 6 <. 17 push( 17 ); push( 6 ); push( 7 ); push( 16 ); push( 15 ); System.out.print( "Original List: " ); printList(head); deletePrimeNodes(head); System.out.print( "\nModified List: " ); printList(head); } } // This code is contributed by Arnab Kundu |
Python3
# Python3 implementation to delete all # prime nodes from the doubly # linked list 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 check if a number is prime def isPrime(n): # Corner cases if (n < = 1 ): return False if (n < = 3 ): return True # This is checked so that we can skip # middle five numbers in below loop if (n % 2 = = 0 or n % 3 = = 0 ): return False for i in range ( 5 , n + 1 , 6 ): if (i * i < n + 2 and (n % i = = 0 or n % (i + 2 ) = = 0 )): return False return True # 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 None # 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 return head_ref # function to delete all prime nodes # from the doubly linked list def deletePrimeNodes(head_ref): ptr = head_ref #next while (ptr ! = None ): next = ptr. next # if true, delete node 'ptr' if (isPrime(ptr.data)): 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 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 ) print ( "Original List: " , end = "") printList(head) deletePrimeNodes(head) print ( "\nModified List: " , end = "") printList(head) # This code is contributed by AbhiThakur |
C#
// C# implementation to delete all // prime nodes from the doubly // linked list 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 check if a number is prime static Boolean isPrime( int n) { // Corner cases if (n <= 1) return false ; if (n <= 3) return true ; // This is checked so that we can skip // middle five numbers in below loop if (n % 2 == 0 || n % 3 == 0) return false ; for ( int i = 5; i * i <= n; i = i + 6) if (n % i == 0 || n % (i + 2) == 0) return false ; return true ; } // 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 prime nodes // from the doubly linked list static Node deletePrimeNodes(Node head_ref) { Node ptr = head_ref; Node next; while (ptr != null ) { next = ptr.next; // if true, delete node 'ptr' if (isPrime(ptr.data)) 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 program public static void Main() { // 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); Console.Write( "Original List: " ); printList(head); head = deletePrimeNodes(head); Console.Write( "\nModified List: " ); printList(head); } } // This code is contributed by Rajput-Ji |
Javascript
<script> // javascript implementation to delete all // prime nodes from the doubly // linked list // 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 check if a number is prime function isPrime(n) { // Corner cases if (n <= 1) return false ; if (n <= 3) return true ; // This is checked so that we can skip // middle five numbers in below loop if (n % 2 == 0 || n % 3 == 0) return false ; for (i = 5; i * i <= n; i = i + 6) if (n % i == 0 || n % (i + 2) == 0) return false ; return true ; } // 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 prime nodes // from the doubly linked list function deletePrimeNodes(head_ref) { var ptr = head_ref; var next; while (ptr != null ) { next = ptr.next; // if true, delete node 'ptr' if (isPrime(ptr.data)) 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 program // 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); document.write( "Original List: " ); printList(head); head = deletePrimeNodes(head); document.write( "<br/>Modified List: " ); printList(head); // This code contributed by Rajput-Ji </script> |
Original List: 15 16 7 6 17 Modified List: 15 16 6
Complexity Analysis:
- Time Complexity: O(N), where N is the total number of nodes.
- Space Complexity: O(1) since using constant variables
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