이중 연결 리스트 (DoubleLinkedList)

#pragma once

#include <iostream>
using namespace std;

struct Node
{
	int data;
	Node* prev;		// Previous 이전
	Node* next;
};

class DoubleLinkedList
{
private:
	int m_count;
	Node* m_head;
	Node* m_tail;

public:
	DoubleLinkedList();
	~DoubleLinkedList();

	void InsertToHead(int _item);
	void InsertToTail(int _item);
	void Delete(int _position);
	int Retrieve(int _position);

	bool IsEmpty();
	int GetLength();
    
};

DoubleLinkedList.h

 

 

#include "DoubleLinkedList.h"

DoubleLinkedList::DoubleLinkedList() :m_count(0), m_head(nullptr), m_tail(nullptr)
{
}

DoubleLinkedList::~DoubleLinkedList()
{
}

void DoubleLinkedList::InsertToHead(int _item)
{
	Node* temp = new Node;
	temp->data = _item;

	if (m_count == 0)
		m_head = m_tail = temp;
	else
	{
		temp->next = m_head;
		m_head->prev = temp;
		m_head = temp;
	}

	m_count++;

}

void DoubleLinkedList::InsertToTail(int _item)
{
	Node* temp = new Node;
	temp->data = _item;

	if (m_count == 0)
		m_head = m_tail = temp;
	else
	{
		temp->prev = m_tail;
		m_tail->next = temp;
		m_tail = temp;
	}

	m_count++;
}

void DoubleLinkedList::Delete(int _position)
{
	Node* deleteNode;
	Node* currentNode = m_head;

	for (int i = 0; i < _position - 1; i++)
		m_head = m_head->next;

	if (_position == 1)
	{
		if (m_count > 1)
		{
			deleteNode = m_head;
			m_head = m_head->next;

			delete deleteNode;
		}
		else
		{
			deleteNode = m_head;
			m_head = m_tail = nullptr;

			delete deleteNode;
		}

		m_count--;

	}
	else if (_position == m_count)
	{
		deleteNode = m_head;
		m_head = m_head->prev;
		m_tail = m_head;

		delete deleteNode;

		m_head = currentNode;
		m_count--;

	}
	else
	{
		m_head->prev->next = m_head->next;
		m_head->next->prev = m_head->prev;

		deleteNode = m_head;
		delete deleteNode;

		m_head = currentNode;
		m_count--;

	}

}

int DoubleLinkedList::Retrieve(int _position)
{
	Node* temp = m_head;

	for (int i = 0; i < _position - 1; i++)
		m_head = m_head->next;

	int tempNum = m_head->data;
	m_head = temp;

	return tempNum;
}

bool DoubleLinkedList::IsEmpty()
{
	return m_count == 0;
}

int DoubleLinkedList::GetLength()
{
	return m_count;
}

DoubleLinkedList.cpp