Sum and Product of all even digit sum Nodes of a Singly Linked List

Given a singly linked list containing N nodes, the task is to find the sum and product of all the nodes from the list whose data value has an even digit sum.

Examples:

Input: 15 -> 16 -> 8 -> 6 -> 13
Output:
Sum = 42
Product = 9360
Explanation:
The sum of all digit of number in linked list are:
15 = 1 + 5 = 6
16 = 1 + 6 = 7
8 = 8
6 = 6
13 = 1 + 3 = 4
The list contains 4 Even Digit Sum data values 15, 8, 6 and 13.
Sum = 15 + 8 + 6 + 13 = 42
Product = 15 * 8 * 6 * 13 = 9360

Input: 5 -> 3 -> 4 -> 2 -> 9
Output:
Sum = 6
Product = 8
Explanation:
The list contains 2 Even Digit Sum data values 4 and 2.
Sum = 4 + 2 = 6
Product = 4 * 2 = 8

Approach: The idea is to traverse the given linked list and check whether the sum of all the digits of current node value is even or not. If yes include the current node value to the resultant sum and the resultant product Else check for the next node value.



Below is the implementation of the above approach:

C++

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// C++ program for the above approach
  
#include <bits/stdc++.h>
using namespace std;
  
// Node of Linked List
struct Node {
    int data;
    Node* next;
};
  
// Function to insert a node at the
// beginning of the singly Linked List
void push(Node** head_ref, int new_data)
{
    // Allocate new node
    Node* new_node
        = (Node*)malloc(
            sizeof(struct Node));
  
    // Insert the data
    new_node->data = new_data;
  
    // Link old list to the new node
    new_node->next = (*head_ref);
  
    // Move head to point the new node
    (*head_ref) = new_node;
}
  
// Function to find the digit sum
// for a number
int digitSum(int num)
{
    int sum = 0;
    while (num) {
        sum += (num % 10);
        num /= 10;
    }
  
    // Return the sum
    return sum;
}
  
// Function to find the required
// sum and product
void sumAndProduct(Node* head_ref)
{
  
    // Initialise the sum and product
    // to 0 and 1 respectively
    int prod = 1;
    int sum = 0;
  
    Node* ptr = head_ref;
  
    // Traverse the given linked list
    while (ptr != NULL) {
  
        // If current node has even
        // digit sum then include it in
        // resultant sum and product
        if (!(digitSum(ptr->data) & 1)) {
  
            // Find the sum and the product
            prod *= ptr->data;
            sum += ptr->data;
        }
  
        ptr = ptr->next;
    }
  
    // Print the final Sum and Product
    cout << "Sum = " << sum << endl;
    cout << "Product = " << prod;
}
  
// Driver Code
int main()
{
    // Head of the linked list
    Node* head = NULL;
  
    // Create the linked list
    // 15 -> 16 -> 8 -> 6 -> 13
    push(&head, 13);
    push(&head, 6);
    push(&head, 8);
    push(&head, 16);
    push(&head, 15);
  
    // Function call
    sumAndProduct(head);
  
    return 0;
}

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Java

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// Java program for the above approach
  
class GFG{
  
// Node of Linked List
static class Node {
    int data;
    Node next;
};
  
// Function to insert a node at the
// beginning of the singly Linked List
static Node push(Node head_ref, int new_data)
{
    // Allocate new node
    Node new_node
        = new Node();
  
    // Insert the data
    new_node.data = new_data;
  
    // Link old list to the new node
    new_node.next = head_ref;
  
    // Move head to point the new node
    head_ref = new_node;
    return head_ref;
}
  
// Function to find the digit sum
// for a number
static int digitSum(int num)
{
    int sum = 0;
    while (num > 0) {
        sum += (num % 10);
        num /= 10;
    }
  
    // Return the sum
    return sum;
}
  
// Function to find the required
// sum and product
static void sumAndProduct(Node head_ref)
{
  
    // Initialise the sum and product
    // to 0 and 1 respectively
    int prod = 1;
    int sum = 0;
  
    Node ptr = head_ref;
  
    // Traverse the given linked list
    while (ptr != null) {
  
        // If current node has even
        // digit sum then include it in
        // resultant sum and product
        if ((digitSum(ptr.data) %2 != 1)) {
  
            // Find the sum and the product
            prod *= ptr.data;
            sum += ptr.data;
        }
  
        ptr = ptr.next;
    }
  
    // Print the final Sum and Product
    System.out.print("Sum = " + sum +"\n");
    System.out.print("Product = " + prod);
}
  
// Driver Code
public static void main(String[] args)
{
    // Head of the linked list
    Node head = null;
  
    // Create the linked list
    // 15.16.8.6.13
    head = push(head, 13);
    head = push(head, 6);
    head = push(head, 8);
    head = push(head, 16);
    head = push(head, 15);
  
    // Function call
    sumAndProduct(head);
  
}
}
  
// This code is contributed by 29AjayKumar

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C#

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// C# program for the above approach
using System;
  
class GFG{
  
// Node of Linked List
class Node
{
    public int data;
    public Node next;
};
  
// Function to insert a node at the
// beginning of the singly Linked List
static Node push(Node head_ref, int new_data)
{
    // Allocate new node
    Node new_node = new Node();
  
    // Insert the data
    new_node.data = new_data;
  
    // Link old list to the new node
    new_node.next = head_ref;
  
    // Move head to point the new node
    head_ref = new_node;
    return head_ref;
}
  
// Function to find the digit sum
// for a number
static int digitSum(int num)
{
    int sum = 0;
    while (num > 0) 
    {
        sum += (num % 10);
        num /= 10;
    }
  
    // Return the sum
    return sum;
}
  
// Function to find the required
// sum and product
static void sumAndProduct(Node head_ref)
{
  
    // Initialise the sum and product
    // to 0 and 1 respectively
    int prod = 1;
    int sum = 0;
  
    Node ptr = head_ref;
  
    // Traverse the given linked list
    while (ptr != null)
    {
  
        // If current node has even
        // digit sum then include it in
        // resultant sum and product
        if ((digitSum(ptr.data) % 2 != 1))
        {
  
            // Find the sum and the product
            prod *= ptr.data;
            sum += ptr.data;
        }
  
        ptr = ptr.next;
    }
  
    // Print the readonly Sum and Product
    Console.Write("Sum = " + sum + "\n");
    Console.Write("Product = " + prod);
}
  
// Driver Code
public static void Main(String[] args)
{
    // Head of the linked list
    Node head = null;
  
    // Create the linked list
    // 15.16.8.6.13
    head = push(head, 13);
    head = push(head, 6);
    head = push(head, 8);
    head = push(head, 16);
    head = push(head, 15);
  
    // Function call
    sumAndProduct(head);
  
}
}
  
// This code is contributed by Rohit_ranjan

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Output:

Sum = 42
Product = 9360

Time Complexity: O(N), where N is the number of nodes in the linked list.

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Improved By : 29AjayKumar, Rohit_ranjan