Question

1. Given the already build class and struct for singly linked list, write a recursive function that finds the minimum value of Singly Linked List (please make use of a helper function)

2. Given the already built class and struct for singly linked list, write a recursive function that finds the sum of a singly linked list (please make sure of a helper function)

Answer 1

#include <iostream>
using namespace std;

// Node of Linked List
struct Node
{
    int data;
    Node *next;
};
// Linked List Class
class LL
{
    private:
        Node *head,*tail;
    public:
        LL() // constructor
        {
            head = NULL; // initially head and tail will be null
            tail = NULL;
        }

        void insertNode(int elem) // add a Node in the list
        {
            Node *newNode = new Node; // create a new node with given element and next will be null
            newNode->data = elem;
            newNode->next = NULL;

            if(head == NULL) // if head is null then make new node as head
            {
                head = newNode;
                tail = newNode;
            }
            else // else insert new node at tail and make tail to point to its next
            {
                tail->next = newNode;
                tail = tail->next;
            }
        }

        int minimumHelper(Node* head, int min)
        {
            if(head == NULL) // if head is null return min
                return min;
            if(min > head->data) // if min is greater than head data then update the min
                min = head->data;
            minimumHelper(head->next,min); // recursive call to minimum helper with head next and min
        }
        int minimum()
        {
            Node *temp = head; // we will pass temp as we don't want modification in head
            return minimumHelper(temp,INT_MAX); // call minimumHelper with temp and Maximum Integer value possible
        }

        int sumHelper(Node* head, int sum)
        {
            if(head == NULL)// if head is null then return the sum
                return sum;

            sum += head->data; // update the sum
            sumHelper(head->next,sum); // recursive call to sumHelper with head next and sum
        }
        int sum()
        {
            Node *temp = head;
            return sumHelper(temp,0); // call sumHelper with temp and 0 as current sum is 0
        }
};
int main()
{
    LL list;
    list.insertNode(1);
    list.insertNode(2);
    list.insertNode(-3);
    list.insertNode(4);
    list.insertNode(5);

    cout<<"Our Linked List is : 1 -> 2 -> -3 -> 4 -> 5"<<endl;
    int min = list.minimum();
    cout<<"Minimum in List is : "<<min<<endl;
    int total_sum = list.sum();
    cout<<"Sum of elements in List is : "<<total_sum<<endl;

    return 0;
}

Output:-