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Create new linked list from two given linked list with greater element at each node

Given two linked list of the same size, the task is to create a new linked list using those linked lists. The condition is that the greater node among both linked list will be added to the new liked list.

Examples:

Input:  list1 = 5->2->3->8
list2 = 1->7->4->5
Output:  New list = 5->7->4->8

Input: list1 = 2->8->9->3
list2 = 5->3->6->4
Output:  New list = 5->8->9->4

Approach: We traverse both the linked list at the same time and compare node of both lists. The node which is greater among them will be added to the new linked list. We do this for each node.

C++

// C++ program to create a new linked list 
// from two given linked list 
// of the same size with 
// the greater element among the two at each node 
  
#include <iostream> 
using namespace std; 
  
// Representation of node 
struct Node { 
    int data; 
    Node* next; 
}; 
  
// Function to insert node in a linked list 
void insert(Node** root, int item) 
{ 
    Node *ptr, *temp; 
    temp = new Node; 
    temp->data = item; 
    temp->next = NULL; 
  
    if (*root == NULL) 
        *root = temp; 
    else { 
        ptr = *root; 
        while (ptr->next != NULL) 
            ptr = ptr->next; 
  
        ptr->next = temp; 
    } 
} 
  
// Function which returns new linked list 
Node* newList(Node* root1, Node* root2) 
{ 
    Node *ptr1 = root1, *ptr2 = root2, *ptr; 
    Node *root = NULL, *temp; 
  
    while (ptr1 != NULL) { 
        temp = new Node; 
        temp->next = NULL; 
  
        // Compare for greater node 
        if (ptr1->data < ptr2->data) 
            temp->data = ptr2->data; 
        else
            temp->data = ptr1->data; 
  
        if (root == NULL) 
            root = temp; 
        else { 
            ptr = root; 
            while (ptr->next != NULL) 
                ptr = ptr->next; 
  
            ptr->next = temp; 
        } 
        ptr1 = ptr1->next; 
        ptr2 = ptr2->next; 
    } 
    return root; 
} 
  
void display(Node* root) 
{ 
    while (root != NULL) { 
        cout << root->data << "->"; 
        root = root->next; 
    } 
  
    cout << endl; 
} 
  
// Driver code 
int main() 
{ 
    Node *root1 = NULL, *root2 = NULL, *root = NULL; 
  
    // First linked list 
    insert(&root1, 5); 
    insert(&root1, 2); 
    insert(&root1, 3); 
    insert(&root1, 8); 
  
    cout << "First List:  "; 
    display(root1); 
  
    // Second linked list 
    insert(&root2, 1); 
    insert(&root2, 7); 
    insert(&root2, 4); 
    insert(&root2, 5); 
  
    cout << "Second List: "; 
    display(root2); 
  
    root = newList(root1, root2); 
    cout << "New List:    "; 
    display(root); 
    return 0; 
} 

Java

// Java program to create a new linked list  
// from two given linked list  
// of the same size with  
// the greater element among the two at each node  
import java.util.*; 
  
class GFG 
{ 
  
// Representation of node  
static class Node  
{  
    int data;  
    Node next;  
};  
  
// Function to insert node in a linked list  
static Node insert(Node root, int item)  
{  
    Node ptr, temp;  
    temp = new Node();  
    temp.data = item;  
    temp.next = null;  
  
    if (root == null)  
        root = temp;  
    else {  
        ptr = root;  
        while (ptr.next != null)  
            ptr = ptr.next;  
  
        ptr.next = temp;  
    }  
    return root; 
}  
  
// Function which returns new linked list  
static Node newList(Node root1, Node root2)  
{  
    Node ptr1 = root1, ptr2 = root2, ptr;  
    Node root = null, temp;  
  
    while (ptr1 != null) {  
        temp = new Node();  
        temp.next = null;  
  
        // Compare for greater node  
        if (ptr1.data < ptr2.data)  
            temp.data = ptr2.data;  
        else
            temp.data = ptr1.data;  
  
        if (root == null)  
            root = temp;  
        else {  
            ptr = root;  
            while (ptr.next != null)  
                ptr = ptr.next;  
  
            ptr.next = temp;  
        }  
        ptr1 = ptr1.next;  
        ptr2 = ptr2.next;  
    }  
    return root;  
}  
  
static void display(Node root)  
{  
    while (root != null)  
    {  
        System.out.print( root.data + "->");  
        root = root.next;  
    }  
    System.out.println(); 
}  
  
// Driver code  
public static void main(String args[]) 
{  
    Node root1 = null, root2 = null, root = null;  
  
    // First linked list  
    root1=insert(root1, 5);  
    root1=insert(root1, 2);  
    root1=insert(root1, 3);  
    root1=insert(root1, 8);  
  
    System.out.print("First List: ");  
    display(root1);  
  
    // Second linked list  
    root2=insert(root2, 1);  
    root2=insert(root2, 7);  
    root2=insert(root2, 4);  
    root2=insert(root2, 5);  
  
    System.out.print( "Second List: ");  
    display(root2);  
  
    root = newList(root1, root2);  
    System.out.print("New List: ");  
    display(root);  
}  
} 
  
// This code is contributed by Arnab Kundu 

Python3

# Python3 program to create a  
# new linked list from two given  
# linked list of the same size with 
# the greater element among the two 
# at each node 
  
# Node class  
class Node:  
  
    # Function to initialise the node object  
    def __init__(self, data):  
        self.data = data  
        self.next = None
  
# Function to insert node in a linked list 
def insert(root, item): 
  
    temp = Node(0) 
    temp.data = item 
    temp.next = None
  
    if (root == None): 
        root = temp 
    else : 
        ptr = root 
        while (ptr.next != None): 
            ptr = ptr.next
  
        ptr.next = temp 
          
    return root 
  
# Function which returns new linked list 
def newList(root1, root2): 
  
    ptr1 = root1 
    ptr2 = root2 
      
    root = None
    while (ptr1 != None) : 
        temp = Node(0) 
        temp.next = None
  
        # Compare for greater node 
        if (ptr1.data < ptr2.data): 
            temp.data = ptr2.data 
        else: 
            temp.data = ptr1.data 
  
        if (root == None): 
            root = temp 
        else : 
            ptr = root 
            while (ptr.next != None): 
                ptr = ptr.next
  
            ptr.next = temp 
          
        ptr1 = ptr1.next
        ptr2 = ptr2.next
      
    return root 
  
def display(root): 
  
    while (root != None) : 
        print(root.data, "->", end = " ") 
        root = root.next
      
    print(" "); 
  
# Driver Code  
if __name__=='__main__':  
  
    root1 = None
    root2 = None
    root = None
  
    # First linked list 
    root1 = insert(root1, 5) 
    root1 = insert(root1, 2) 
    root1 = insert(root1, 3) 
    root1 = insert(root1, 8) 
  
    print("First List: ", end = " ") 
    display(root1) 
  
    # Second linked list 
    root2 = insert(root2, 1) 
    root2 = insert(root2, 7) 
    root2 = insert(root2, 4) 
    root2 = insert(root2, 5) 
  
    print("Second List: ", end = " ") 
    display(root2) 
  
    root = newList(root1, root2) 
    print("New List: ", end = " ") 
    display(root) 
  
# This code is contributed by Arnab Kundu 

C#

// C# program to create a new linked list  
// from two given linked list  
// of the same size with  
// the greater element among the two at each node  
using System; 
      
class GFG 
{ 
  
// Representation of node  
public class Node  
{  
    public int data;  
    public Node next;  
};  
  
// Function to insert node in a linked list  
static Node insert(Node root, int item)  
{  
    Node ptr, temp;  
    temp = new Node();  
    temp.data = item;  
    temp.next = null;  
  
    if (root == null)  
        root = temp;  
    else
    {  
        ptr = root;  
        while (ptr.next != null)  
            ptr = ptr.next;  
  
        ptr.next = temp;  
    }  
    return root; 
}  
  
// Function which returns new linked list  
static Node newList(Node root1, Node root2)  
{  
    Node ptr1 = root1, ptr2 = root2, ptr;  
    Node root = null, temp;  
  
    while (ptr1 != null) 
    {  
        temp = new Node();  
        temp.next = null;  
  
        // Compare for greater node  
        if (ptr1.data < ptr2.data)  
            temp.data = ptr2.data;  
        else
            temp.data = ptr1.data;  
  
        if (root == null)  
            root = temp;  
        else 
        {  
            ptr = root;  
            while (ptr.next != null)  
                ptr = ptr.next;  
  
            ptr.next = temp;  
        }  
        ptr1 = ptr1.next;  
        ptr2 = ptr2.next;  
    }  
    return root;  
}  
  
static void display(Node root)  
{  
    while (root != null)  
    {  
        Console.Write( root.data + "->");  
        root = root.next;  
    }  
    Console.WriteLine(); 
}  
  
// Driver code  
public static void Main(String []args) 
{  
    Node root1 = null, root2 = null, root = null;  
  
    // First linked list  
    root1 = insert(root1, 5);  
    root1 = insert(root1, 2);  
    root1 = insert(root1, 3);  
    root1 = insert(root1, 8);  
  
    Console.Write("First List: ");  
    display(root1);  
  
    // Second linked list  
    root2 = insert(root2, 1);  
    root2 = insert(root2, 7);  
    root2 = insert(root2, 4);  
    root2 = insert(root2, 5);  
  
    Console.Write( "Second List: ");  
    display(root2);  
  
    root = newList(root1, root2);  
    Console.Write("New List: ");  
    display(root);  
}  
} 
  
// This code has been contributed by 29AjayKumar 

Output:

First List:  5->2->3->8->
Second List: 1->7->4->5->
New List:    5->7->4->8->

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