Question

In C++

Assuming:
struct node
{
    int data;
    node * next;
};

and 
copyList(node * head);

Write a recursive function (copyList(node * head)) that will create a copy of the singly linked list.

Answer 1

#include <iostream>

using namespace std;

struct node
{
    int data;
    node * next;
};

node *copyList(node * head) {
    if(head == NULL) {
        return NULL;
    } else {
        node *copy = new node;
        copy->data = head->data;
        copy->next = copyList(head->next);
        return copy;
    }
}

int main() {
    node *original_list = new node;
    original_list->data = 5;
    original_list->next = new node;
    original_list->next->data = 2;
    original_list->next->next = new node;
    original_list->next->next->data = 9;
    original_list->next->next->next = NULL;

    node *copy_list = copyList(original_list);
    node *temp = copy_list;
    while (temp != NULL) {
        cout << temp->data << " ";
        temp = temp->next;
    }
    cout << endl;

    return 0;
}