# Product of all prime nodes in a Doubly Linked List

• Last Updated : 11 Jun, 2021

Given a doubly linked list containing N nodes. The task is to find the product of all prime nodes.
Example:

Input: List = 15 <=> 16 <=> 6 <=> 7 <=> 17
Output: Product of Prime Nodes: 119
Input: List = 5 <=> 3 <=> 4 <=> 2 <=> 9
Output: Product of Prime Nodes: 30

Attention reader! Don’t stop learning now. Get hold of all the important DSA concepts with the DSA Self Paced Course at a student-friendly price and become industry ready.  To complete your preparation from learning a language to DS Algo and many more,  please refer Complete Interview Preparation Course.

In case you wish to attend live classes with experts, please refer DSA Live Classes for Working Professionals and Competitive Programming Live for Students.

Approach:

• Initialize a pointer temp with the head of the linked list and a product variable with 1.
• Start traversing the linked list using a loop until all the nodes get traversed.
• If node value is prime then multiply the value of the current node to the product i.e. product *= current_node-> data.
• Increment the pointer to the next node of linked list i.e. temp = temp -> next.
• Return the product.

Below is the implementation of the above approach:

## C++

 `// C++ implementation to product all``// prime nodes from the doubly``// linked list``#include ` `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 product all prime nodes``// from the doubly linked list``int` `prodOfPrime(Node** head_ref)``{``    ``Node* ptr = *head_ref;``    ``Node* next;``    ``// variable prod = 1 for multiplying nodes value``    ``int` `prod = 1;``    ``// traverse list till last node``    ``while` `(ptr != NULL) {``        ``next = ptr->next;``        ``// if number is prime then``        ``// multiply to product``        ``if` `(isPrime(ptr->data))``            ``prod = prod * ptr->data;``        ``ptr = next;``    ``}` `    ``// return product``    ``return` `prod;``}` `// 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` `prod = prodOfPrime(&head);` `    ``cout << ``"Product of Prime Nodes : "` `<< prod;` `    ``return` `0;``}`

## Java

 `// Java implementation to product all``// prime nodes from the doubly``// linked list` `// Node of the doubly linked list``class` `Node``{``    ``int` `data;``    ``Node next, prev;` `    ``Node(``int` `d)``    ``{``        ``data = d;``        ``next = ``null``;``        ``prev = ``null``;``    ``}``}` `class` `DLL``{``    ``// function to insert a node at the beginning``    ``// of the Doubly Linked List``    ``static` `Node push(Node head, ``int` `data)``    ``{``        ``Node newNode = ``new` `Node(data);``        ``newNode.next = head;``        ``newNode.prev = ``null``;``        ``if` `(head != ``null``)``            ``head.prev = newNode;``        ``head = newNode;` `        ``return` `head;``    ``}` `    ``// 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 product all prime nodes``    ``// from the doubly linked list``    ``static` `int` `prodOfPrime(Node node)``    ``{``        ``// variable prod = 1 for multiplying nodes value``        ``int` `prod = ``1``;``        ` `        ``// traverse list till last node``        ``while` `(node != ``null``)``        ``{``            ``// check is node value is Prime``            ``// if true then multiply to prod``            ``if` `(isPrime(node.data))``                ``prod *= node.data;``            ``node = node.next;``        ``}``        ``// return product``        ``return` `prod;``    ``}` `    ``// Driver Program``    ``public` `static` `void` `main(String[] args)``    ``{``        ``// Start with empty list``        ``Node head = ``null``;` `        ``// create the doubly linked list``        ``// 15 <-> 16 <-> 7 <-> 6 <-> 17``        ``head = push(head, ``17``);``        ``head = push(head, ``7``);``        ``head = push(head, ``6``);``        ``head = push(head, ``9``);``        ``head = push(head, ``10``);``        ``head = push(head, ``16``);``        ``head = push(head, ``15``);` `        ``int` `prod = prodOfPrime(head);``        ``System.out.println(``"Product of Prime Nodes: "` `+ prod);``    ``}``}` `// This code is contributed by Vivekkumar Singh`

## Python3

 `# Python3 implementation to product all``# prime nodes from the doubly``# linked list` `# Node of the doubly linked list``class` `Node:``    ` `    ``def` `__init__(``self``, data):``        ``self``.data ``=` `data``        ``self``.prev ``=` `None``        ``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(``0``)` `    ``# put in the data``    ``new_node.data ``=` `new_data` `    ``# since we are multiplying 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``    ``i ``=` `5``    ``while` `( i ``*` `i <``=` `n ):``        ``if` `(n ``%` `i ``=``=` `0` `or` `n ``%` `(i ``+` `2``) ``=``=` `0``):``            ``return` `False``        ``i ``+``=` `6``;` `    ``return` `True` `# function to product all prime nodes``# from the doubly linked list``def` `prodOfPrime(head_ref):` `    ``ptr ``=` `head_ref``    ``next` `=` `None``    ` `    ``# variable prod = 1 for multiplying nodes value``    ``prod ``=` `1``    ` `    ``# traverse list till last node``    ``while` `(ptr !``=` `None``):``        ``next` `=` `ptr.``next``        ` `        ``# if number is prime then``        ``# multiply to product``        ``if` `(isPrime(ptr.data)):``            ``prod ``=` `prod ``*` `ptr.data``        ``ptr ``=` `next` `    ``# return product``    ``return` `prod` `# 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``)``    ``prod ``=` `prodOfPrime(head)` `    ``print``(``"Product of Prime Nodes : "``, prod)` `# This code is contributed by Arnab Kundu`

## C#

 `// C# implementation to product all``// prime nodes from the doubly``// linked list``using` `System;` `// Node of the doubly linked list``public` `class` `Node``{``    ``public` `int` `data;``    ``public` `Node next, prev;` `    ``public` `Node(``int` `d)``    ``{``        ``data = d;``        ``next = ``null``;``        ``prev = ``null``;``    ``}``}` `class` `DLL``{``    ``// function to insert a node at the beginning``    ``// of the Doubly Linked List``    ``static` `Node push(Node head, ``int` `data)``    ``{``        ``Node newNode = ``new` `Node(data);``        ``newNode.next = head;``        ``newNode.prev = ``null``;``        ``if` `(head != ``null``)``            ``head.prev = newNode;``        ``head = newNode;` `        ``return` `head;``    ``}` `    ``// 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 product all prime nodes``    ``// from the doubly linked list``    ``static` `int` `prodOfPrime(Node node)``    ``{``        ``// variable prod = 1 for multiplying nodes value``        ``int` `prod = 1;``        ` `        ``// traverse list till last node``        ``while` `(node != ``null``)``        ``{``            ``// check is node value is Prime``            ``// if true then multiply to prod``            ``if` `(isPrime(node.data))``                ``prod *= node.data;``            ``node = node.next;``        ``}``        ``// return product``        ``return` `prod;``    ``}` `    ``// Driver code``    ``public` `static` `void` `Main(String []args)``    ``{``        ``// Start with empty list``        ``Node head = ``null``;` `        ``// create the doubly linked list``        ``// 15 <-> 16 <-> 7 <-> 6 <-> 17``        ``head = push(head, 17);``        ``head = push(head, 7);``        ``head = push(head, 6);``        ``head = push(head, 9);``        ``head = push(head, 10);``        ``head = push(head, 16);``        ``head = push(head, 15);` `        ``int` `prod = prodOfPrime(head);``        ``Console.WriteLine(``"Product of Prime Nodes: "` `+ prod);``    ``}``}` `// This code is contributed by Arnab Kundu`

## Javascript

 ``
Output:
`Product of Prime Nodes : 119`

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

My Personal Notes arrow_drop_up