Replace even nodes of a doubly linked list with the elements of array - GeeksforGeeks

03 Nov, 2021
Given a doubly linked list and an array with only odd values. Both are of equal size N. The task is replace all node which have even value with the Array elements from left to right. 
Examples: 
Input : List = 6 9 8 7 4 Arr[] = {3, 5, 23, 17, 1} Output : List = 3 9 5 7 23Input : List = 9 14 7 12 8 13 Arr[] = {5, 1, 17, 21, 11, 7} Output : List = 9 5 7 1 17 13
 
Approach: The idea is to traverse the nodes of the doubly linked list one by one and get the pointer of the nodes having even data then replace by the value of the array and increment the index of the array and move to the next node in the linked list.Below is the implementation of above approach: 
C++
Java
Python3
C#
Javascript
// C++ implementation to create// odd doubly linked list#include <bits/stdc++.h>using namespace std; // Node of the doubly linked liststruct Node {    int data;    Node *prev, *next;}; // function to insert a node at the beginning// of the Doubly Linked Listvoid 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 make all node is oddvoid makeOddNode(Node** head_ref, int A[], int n){    Node* ptr = *head_ref;    Node* next;    int i = 0;    // traves list till last node    while (ptr != NULL) {        next = ptr->next;        // check if node is even then        // replace it and increment in i        if (ptr->data % 2 == 0) {            ptr->data = A[i];            i++;        }        ptr = next;    }    // return sum of nodes which is divided by K}// function to print nodes in a// given doubly linked listvoid printList(Node* head){    while (head != NULL) {        cout << head->data << " ";        head = head->next;    }} // Driver program to test aboveint main(){    // start with the empty list    Node* head = NULL;     // create the doubly linked list    // 6 <=> 9 <=> 8 <=> 7 <=> 4    int Arr[] = { 3, 5, 23, 17, 1 };    push(&head, 4);    push(&head, 7);    push(&head, 8);    push(&head, 9);    push(&head, 6);    int n = sizeof(Arr) / sizeof(Arr[0]);    cout << "Original List: ";    printList(head);    cout << endl;    makeOddNode(&head, Arr, n);    cout << "New odd List: ";    printList(head);}
// Java implementation to create// odd doubly linked listclass GFG{ // Node of the doubly linked liststatic class Node{    int data;    Node prev, next;}; // function to insert a node at the beginning// of the Doubly Linked Liststatic 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 make all node is oddstatic Node makeOddNode(Node head_ref, int A[], int n){    Node ptr = head_ref;    Node next;    int i = 0;    // traves list till last node    while (ptr != null)    {        next = ptr.next;                 // check if node is even then        // replace it and increment in i        if (ptr.data % 2 == 0)        {             ptr.data = A[i];            i++;        }        ptr = next;    }         // return sum of nodes which is divided by K    return head_ref;} // function to print nodes in a// given doubly linked liststatic void printList(Node head){    while (head != null)    {        System.out.print( head.data + " ");        head = head.next;    }} // Driver codepublic static void main(String args[]){    // start with the empty list    Node head = null;     // create the doubly linked list    // 6 <=> 9 <=> 8 <=> 7 <=> 4    int Arr[] = { 3, 5, 23, 17, 1 };    head = push(head, 4);    head = push(head, 7);    head = push(head, 8);    head = push(head, 9);    head = push(head, 6);    int n = Arr.length;    System.out.print( "Original List: ");    printList(head);    System.out.println();    head = makeOddNode(head, Arr, n);    System.out.print("New odd List: ");    printList(head);}} // This code is contributed by Arnab Kundu
# Python3 implementation to# create odd doubly linked list # Node of the doubly linked listclass 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 Listdef push(head_ref, new_data):     # allocate node    new_node = Node(new_data)     # 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 make all node is odddef makeOddNode(head_ref, A, n):     ptr = head_ref    i = 0         # traves list till last node    while ptr != None:                 next = ptr.next                 # check if node is even then        # replace it and increment in i        if ptr.data % 2 == 0:            ptr.data = A[i]            i += 1                 ptr = next         # return sum of nodes which is divided by K # Function to print nodes in a# given doubly linked listdef printList(head):     while head != None:        print(head.data, end = " ")        head = head.next # Driver Codeif __name__ == "__main__":     # start with the empty list    head = None     # create the doubly linked list    # 6 <=> 9 <=> 8 <=> 7 <=> 4    Arr = [3, 5, 23, 17, 1]    head = push(head, 4)    head = push(head, 7)    head = push(head, 8)    head = push(head, 9)    head = push(head, 6)    n = len(Arr)         print("Original List:", end = " ")    printList(head)    print()         makeOddNode(head, Arr, n)    print("New odd List:", end = " ")    printList(head) # This code is contributed by Rituraj Jain
// C# implementation to create// odd doubly linked listusing System;     class GFG{ // Node of the doubly linked listpublic class Node{    public int data;    public Node prev, next;}; // function to insert a node at the beginning// of the Doubly Linked Liststatic 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 make all node is oddstatic Node makeOddNode(Node head_ref, int []A, int n){    Node ptr = head_ref;    Node next;    int i = 0;         // traves list till last node    while (ptr != null)    {        next = ptr.next;                 // check if node is even then        // replace it and increment in i        if (ptr.data % 2 == 0)        {             ptr.data = A[i];            i++;        }        ptr = next;    }         // return sum of nodes which is divided by K    return head_ref;} // function to print nodes in a// given doubly linked liststatic void printList(Node head){    while (head != null)    {        Console.Write( head.data + " ");        head = head.next;    }} // Driver codepublic static void Main(String []args){    // start with the empty list    Node head = null;     // create the doubly linked list    // 6 <=> 9 <=> 8 <=> 7 <=> 4    int []Arr = { 3, 5, 23, 17, 1 };    head = push(head, 4);    head = push(head, 7);    head = push(head, 8);    head = push(head, 9);    head = push(head, 6);    int n = Arr.Length;    Console.WriteLine( "Original List: ");    printList(head);    Console.WriteLine();    head = makeOddNode(head, Arr, n);    Console.WriteLine("New odd List: ");    printList(head);}} // This code contributed by Rajput-Ji
<script> // JavaScript implementation to create// odd doubly linked list// Node of the doubly linked listclass 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 point to the new node        (head_ref) = new_node;        return head_ref;    }     // function to make all node is odd    function makeOddNode(head_ref , A , n) {        var ptr = head_ref;        var next;        var i = 0;        // traves list till last node        while (ptr != null) {            next = ptr.next;             // check if node is even then            // replace it and increment in i            if (ptr.data % 2 == 0) {                 ptr.data = A[i];                i++;            }            ptr = next;        }         // return sum of nodes which is divided by K        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        // 6 <=> 9 <=> 8 <=> 7 <=> 4        var Arr = [ 3, 5, 23, 17, 1 ];        head = push(head, 4);        head = push(head, 7);        head = push(head, 8);        head = push(head, 9);        head = push(head, 6);        var n = Arr.length;        document.write("Original List: ");        printList(head);        document.write("<br/>");        head = makeOddNode(head, Arr, n);        document.write("New odd List: ");        printList(head); // This code contributed by umadevi9616 </script>
Original List: 6 9 8 7 4 
New odd List: 3 9 5 7 23
 
Time Complexity: O(N), where N is the total number of nodes. 
rituraj_jain
andrew1234
Rajput-Ji
nidhi_biet
umadevi9616
sooda367
ankita_saini
doubly linked list
Technical Scripter 2018
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