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Delete all Prime Nodes from a Doubly Linked List

  • Last Updated : 27 May, 2021

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 <=> 6
Input: List = 5 <=> 3 <=> 4 <=> 2 <=> 9 
Output: Final List = 5 <=> 4 <=> 9 
 

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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 off 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




// Java implementation to delete all
// prime nodes from the doubly
// linked list
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 off 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)
    {
        System.out.print( head.data + " ");
        head = head.next;
    }
}
 
// Driver program
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);
 
    System.out.print( "Original List: ");
    printList(head);
 
    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 off 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 off 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 off 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 povar 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 prvar 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>
Output: 
Original List: 15 16 7 6 17 
Modified List: 15 16 6

 

Time Complexity: O(N), where N is the total number of nodes.
 




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