# Multiply two numbers represented by Linked Lists

Given two numbers represented by linked lists, write a function that returns the multiplication of these two linked lists.

**Examples:**

Input : 9->4->6 8->4 Output : 79464 Input : 3->2->1 1->2 Output : 3852

**Solution**:

Traverse both lists and generate the required numbers to be multiplied and then return the multiplied values of the two numbers.

Algorithm to generate the number from linked list representation:

1) Initialize a variable to zero 2) Start traversing the linked list 3) Add the value of first node to this variable 4) From the second node, multiply the variable by 10 and also take modulus of this value by 10^9+7 and then add the value of the node to this variable. 5) Repeat step 4 until we reach the last node of the list.

Use the above algorithm with both of linked lists to generate the numbers.

Below is the program for multiplying two numbers represented as linked lists:

## C++

// C++ program to Multiply two numbers // represented as linked lists #include<bits/stdc++.h> #include<stdio.h> using namespace std; // Linked list node struct Node { int data; struct Node* next; }; // Function to create a new node // with given data struct Node *newNode(int data) { struct Node *new_node = (struct Node *) malloc(sizeof(struct Node)); new_node->data = data; new_node->next = NULL; return new_node; } // Function to insert a node at the // beginning of the Linked List void push(struct Node** head_ref, int new_data) { // allocate node struct Node* new_node = newNode(new_data); // link the old list off the new node new_node->next = (*head_ref); // move the head to point to the new node (*head_ref) = new_node; } // Multiply contents of two linked lists long long multiplyTwoLists (Node* first, Node* second) { long long N= 1000000007; long long num1 = 0, num2 = 0; while (first || second){ if(first){ num1 = ((num1)*10)%N + first->data; first = first->next; } if(second) { num2 = ((num2)*10)%N + second->data; second = second->next; } } return ((num1%N)*(num2%N))%N; } // A utility function to print a linked list void printList(struct Node *node) { while(node != NULL) { cout<<node->data; if(node->next) cout<<"->"; node = node->next; } cout<<"\n"; } // Driver program to test above function int main() { struct Node* first = NULL; struct Node* second = NULL; // create first list 9->4->6 push(&first, 6); push(&first, 4); push(&first, 9); printf("First List is: "); printList(first); // create second list 8->4 push(&second, 4); push(&second, 8); printf("Second List is: "); printList(second); // Multiply the two lists and see result cout<<"Result is: "; cout<<multiplyTwoLists(first, second); return 0; }

## Java

// Java program to Multiply two numbers // represented as linked lists import java.util.*; public class GFG{ // Linked list node static class Node { int data; Node next; Node(int data){ this.data = data; next = null; } } // Multiply contents of two linked lists static long multiplyTwoLists(Node first, Node second) { long N = 1000000007; long num1 = 0, num2 = 0; while (first != null || second != null){ if(first != null){ num1 = ((num1)*10)%N + first.data; first = first.next; } if(second != null) { num2 = ((num2)*10)%N + second.data; second = second.next; } } return ((num1%N)*(num2%N))%N; } // A utility function to print a linked list static void printList(Node node) { while(node != null) { System.out.print(node.data); if(node.next != null) System.out.print("->"); node = node.next; } System.out.println(); } // Driver program to test above function public static void main(String args[]) { // create first list 9->4->6 Node first = new Node(9); first.next = new Node(4); first.next.next = new Node(6); System.out.print("First List is: "); printList(first); // create second list 8->4 Node second = new Node(8); second.next = new Node(4); System.out.print("Second List is: "); printList(second); // Multiply the two lists and see result System.out.print("Result is: "); System.out.println(multiplyTwoLists(first, second)); } } // This code is contributed by adityapande88

## Python3

# Python3 to multiply two numbers # represented as Linked Lists # Linked list node class class Node: # Function to initialize the node def __init__(self, data): self.data = data self.next = None # Linked List Class class LinkedList: # Function to initialize the # LinkedList class. def __init__(self): # Initialize head as None self.head = None # Function to insert a node at the # beginning of the Linked List def push(self, new_data): # Create a new Node new_node = Node(new_data) # Make next of the new Node as head new_node.next = self.head # Move the head to point to new Node self.head = new_node # Function to print the Linked List def printList(self): ptr = self.head while (ptr != None): print(ptr.data, end = '') if ptr.next != None: print('->', end = '') ptr = ptr.next print() # Multiply contents of two Linked Lists def multiplyTwoLists(first, second): num1 = 0 num2 = 0 first_ptr = first.head second_ptr = second.head while first_ptr != None or second_ptr != None: if first_ptr != None: num1 = (num1 * 10) + first_ptr.data first_ptr = first_ptr.next if second_ptr != None: num2 = (num2 * 10) + second_ptr.data second_ptr = second_ptr.next return num1 * num2 # Driver code if __name__=='__main__': first = LinkedList() second = LinkedList() # Create first Linked List 9->4->6 first.push(6) first.push(4) first.push(9) # Printing first Linked List print("First list is: ", end = '') first.printList() # Create second Linked List 8->4 second.push(4) second.push(8) # Printing second Linked List print("Second List is: ", end = '') second.printList() # Multiply two linked list and # print the result result = multiplyTwoLists(first, second) print("Result is: ", result) # This code is contributed by kirtishsurangalikar

## Javascript

<script> // Javascript program to Multiply two numbers // represented as linked lists // Linked list node class Node { constructor(data) { this.data=data; this.next = null; } } // Multiply contents of two linked lists function multiplyTwoLists(first,second) { let N = 1000000007; let num1 = 0, num2 = 0; while (first != null || second != null){ if(first != null){ num1 = ((num1)*10)%N + first.data; first = first.next; } if(second != null) { num2 = ((num2)*10)%N + second.data; second = second.next; } } return ((num1%N)*(num2%N))%N; } // A utility function to print a linked list function printList(node) { while(node != null) { document.write(node.data); if(node.next != null) document.write("->"); node = node.next; } document.write("<br>"); } // Driver program to test above function // create first list 9->4->6 let first = new Node(9); first.next = new Node(4); first.next.next = new Node(6); document.write("First List is: "); printList(first); // create second list 8->4 let second = new Node(8); second.next = new Node(4); document.write("Second List is: "); printList(second); // Multiply the two lists and see result document.write("Result is: "); document.write(multiplyTwoLists(first, second)+"<br>"); // This code is contributed by avanitrachhadiya2155 </script>

**Output**

First List is: 9->4->6 Second List is: 8->4 Result is: 79464

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