# C++ Program To Multiply Two Numbers Represented By Linked Lists

• Last Updated : 15 Jun, 2022

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 the first node to this variable
4) From the second node, multiply the variable by 10
and also take the 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 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``#include``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 << ``""``;``}``  ` `// Driver code``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;``}`

Output:

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

Time Complexity: O(max(n1, n2)), where n1 and n2 represents the number of nodes present in the first and second linked list respectively.
Auxiliary Space: O(1), no extra space is required, so it is a constant.

Please refer complete article on Multiply two numbers represented by Linked Lists for more details!

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