Question

You are to write well-formed C++ code that defines and implements a new public member function of the attached doubly linked list data structure, which is implemented using two dummy nodes.

Implement your function using recursion. That is, your new public member function must call a new private, recursive helper function. A non-recursive version of the helper function will get no credit. The helper function should not have any loops at all. Do not use any global variables. Both new functions should call existing member functions when appropriate. Refer to the attached code for the existing functions available. The attachment is for reference only. Write your response in the space below clearly indicating which is the public and which is the private function.   Click here to view the attachment.

You cannot add additional attributes to the class. You may assume the default and copy constructors, and all the operators (e.g., <, <=, ==, +, ++, =, +=, <<) are defined for element type Data_t. The description of the new public function you are to write is:

Iterator findFirst( const Data_t & value );

This function takes one argument and returns an iterator to the node containing the first occurrence of the supplied value, or an iterator to the trailing dummy node if the value is not contained in the list. For example, if the list is

    _head → dummy_node ↔ 10 ↔ 23 ↔ 15 ↔ 23 ↔ 15 ↔ dummy_node ← _tail
                              ↑                        ↑
                         findFirst(23)            findFirst(20)       

then findFirst(20) returns an iterator to the trailing dummy node, but findFirst(23) returns an iterator to the first occurrence of 23..

Answer 1

// code

// Seaction 1

#include <iostream>

using namespace std;

template <class T>

struct Node

{

T data;

Node *next;

};

template <class T>

class linked_list

{

Node<T> *_head, *_trail;

// recursive helper function

Iterator find_first_helper(Node *head, const Data_t &value)

{

// trail node, not found

if (head == this->_trail)

{

return this->_trail;

}

// found

if (head->data == value)

return head;

// recursive call

return find_first_helper(head->next, value);

}

public:

Iterator findFirst(const Data_t &value)

{

// call helper function with 2 next for 2 dummy nodes

return find_first_helper(this->_head->next->next, value);

}

};

int main(int argc, char const *argv[])

{

}

THANK YOU!!! PLZ IGNORE SMALL MISTAKES

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