# Sum of all nodes in a doubly linked list divisible by a given number K

• Difficulty Level : Easy
• Last Updated : 29 Oct, 2021

Given a doubly-linked list containing N nodes and given a number K. The task is to find the sum of all such nodes which are divisible by K.
Examples:

```Input: List = 15 <=> 16 <=> 10 <=> 9 <=> 6 <=> 7 <=> 17
K = 3
Output: Sum = 30

Input: List = 5 <=> 3 <=> 6 <=> 8 <=> 4 <=> 1 <=> 2 <=> 9
K = 2
Output: Sum = 20```

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Approach: The idea is to traverse the doubly linked list and check the nodes one by one. If a node’s value is divisible by K then add that node value to  otherwise continue this process while the end of the list is not reached.
Below is the implementation of the above approach:

## C++

 `// C++ implementation to add``// all nodes value which is``// divided by any given number K``#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 sum all the nodes``// from the doubly linked``// list that are divided by K``int` `sumOfNode(Node** head_ref, ``int` `K)``{``    ``Node* ptr = *head_ref;``    ``Node* next;``    ``// variable sum=0 for add nodes value``    ``int` `sum = 0;``    ``// traves list till last node``    ``while` `(ptr != NULL) {``        ``next = ptr->next;``        ``// check is node value divided by K``        ``// if true then add in sum``        ``if` `(ptr->data % K == 0)``            ``sum += ptr->data;``        ``ptr = next;``    ``}``    ``// return sum of nodes which is divided by K``    ``return` `sum;``}`` ` `// Driver program to test above``int` `main()``{``    ``// start with the empty list``    ``Node* head = NULL;`` ` `    ``// create the doubly linked list``    ``// 15 <-> 16 <-> 10 <-> 9 <-> 6 <-> 7 <-> 17``    ``push(&head, 17);``    ``push(&head, 7);``    ``push(&head, 6);``    ``push(&head, 9);``    ``push(&head, 10);``    ``push(&head, 16);``    ``push(&head, 15);`` ` `    ``int` `sum = sumOfNode(&head, 3);``    ``cout << ``"Sum = "` `<< sum;``}`

## Java

 `// Java implementation to add``// all nodes value which is``// divided by any given number K`` ` `// 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)``    ``{``         ` `        ``// allocate node``        ``Node newNode = ``new` `Node(data);``        ``newNode.next = head;``         ` `        ``// since we are adding at the beginning,``        ``// prev is always NULL``        ``newNode.prev = ``null``;``         ` `        ``// change prev of head node to new node``        ``if` `(head != ``null``)``            ``head.prev = newNode;``             ` `        ``// move the head to point to the new node``        ``head = newNode;`` ` `        ``return` `head;``    ``}`` ` `    ``// function to sum all the nodes``    ``// from the doubly linked``    ``// list that are divided by K``    ``static` `int` `sumOfNode(Node node, ``int` `K) {``        ``// variable sum=0 for add nodes value``        ``int` `sum = ``0``;``        ``// traverse list till last node``        ``while` `(node != ``null``) {``            ``// check is node value divided by K``            ``// if true then add in sum``            ``if` `(node.data % K == ``0``)``                ``sum += node.data;``            ``node = node.next;``        ``}``        ``// return sum of nodes which is divided by K``        ``return` `sum;``    ``}`` ` `    ``// Driver program``    ``public` `static` `void` `main(String[] args) ``    ``{``        ``// start with the empty list``        ``Node head = ``null``;`` ` `        ``// create the doubly linked list``        ``// 15 <-> 16 <-> 10 <-> 9 <-> 6 <-> 7 <-> 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` `sum = sumOfNode(head, ``3``);``        ``System.out.println(``"Sum = "` `+ sum);``    ``}``}`` ` ` ` `// This code is contributed by Vivekkumar Singh`

## Python3

 `# Python3 implementation to add``# all nodes value which is``# divided by any given number K`` ` `# 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 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 sum all the nodes``# from the doubly linked``# list that are divided by K``def` `sumOfNode(head_ref, K):`` ` `    ``ptr ``=` `head_ref``    ``next` `=` `None``     ` `    ``# variable sum=0 for add nodes value``    ``sum` `=` `0``     ` `    ``# traverse list till last node``    ``while` `(ptr !``=` `None``) :``        ``next` `=` `ptr.``next``         ` `        ``# check is node value divided by K``        ``# if true then add in sum``        ``if` `(ptr.data ``%` `K ``=``=` `0``):``            ``sum` `+``=` `ptr.data``        ``ptr ``=` `next``     ` `    ``# return sum of nodes which is divided by K``    ``return` `sum`` ` `# Driver Code``if` `__name__ ``=``=` `"__main__"``: `` ` `    ``# start with the empty list``    ``head ``=` `None`` ` `    ``# create the doubly linked list``    ``# 15 <. 16 <. 10 <. 9 <. 6 <. 7 <. 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``)``  ` `    ``sum` `=` `sumOfNode(head, ``3``)``    ``print``(``"Sum ="``, ``sum``)`` ` `# This code is contributed by Arnab Kundu`

## C#

 `// C# implementation to add ``// all nodes value which is ``// divided by any given number K ``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) ``    ``{ ``         ` `        ``// allocate node ``        ``Node newNode = ``new` `Node(data); ``        ``newNode.next = head; ``         ` `        ``// since we are adding at the beginning, ``        ``// prev is always NULL ``        ``newNode.prev = ``null``; ``         ` `        ``// change prev of head node to new node ``        ``if` `(head != ``null``) ``            ``head.prev = newNode; ``             ` `        ``// move the head to point to the new node ``        ``head = newNode; `` ` `        ``return` `head; ``    ``} `` ` `    ``// function to sum all the nodes ``    ``// from the doubly linked ``    ``// list that are divided by K ``    ``static` `int` `sumOfNode(Node node, ``int` `K)``    ``{ ``        ``// variable sum=0 for add nodes value ``        ``int` `sum = 0; ``        ``// traverse list till last node ``        ``while` `(node != ``null``)``        ``{ ``            ``// check is node value divided by K ``            ``// if true then add in sum ``            ``if` `(node.data % K == 0) ``                ``sum += node.data; ``            ``node = node.next; ``        ``} ``        ``// return sum of nodes which is divided by K ``        ``return` `sum; ``    ``} `` ` `    ``// Driver code ``    ``public` `static` `void` `Main(String []args) ``    ``{ ``        ``// start with the empty list ``        ``Node head = ``null``; `` ` `        ``// create the doubly linked list ``        ``// 15 <-> 16 <-> 10 <-> 9 <-> 6 <-> 7 <-> 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` `sum = sumOfNode(head, 3); ``        ``Console.WriteLine(``"Sum = "` `+ sum); ``    ``} ``} `` ` `// This code is contributed by Arnab Kundu`

## Javascript

 ``
Output:
`Sum = 30`

Time Complexity: O(N)

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