算法与数据结构基础6：C++队列的简单实现

#include <cstdio>
#include <cassert>
#include <iostream>

using namespace std;

class Queue
{
public:
	// **************************************************************************
	// 类的四大函数：构造函数、拷贝构造函数、重载赋值运算符、析构函数
	// **************************************************************************
	Queue();
	Queue(const Queue &Queue);
	Queue& operator=(const Queue &Queue);
	~Queue();

	// **************************************************************************
	// 增删改查
	// **************************************************************************
	int Pop();
	void Push(const int& data);

	unsigned short Size();
	bool IsEmpty();
	void PrintQueue();

private:
	void Free();

private:
	typedef struct Node{
		Node(int d):data(d),next(NULL){}
		int data;
		struct Node* next;
	}Node;

	Node* m_head;
	Node* m_tail;/* 这个变量加得有点鸡肋，最初是想用来操作链表尾，发现只有插入的时候能用，删除的时候用不了，因为没有前指针 */
	unsigned short m_size;
};

// **************************************************************************
// 私有方法
// **************************************************************************
void Queue::Free()
{
	if(m_head){
		Node* tmp = NULL;
		while(m_head){
			tmp = m_head;
			m_head = m_head->next;
			delete tmp;
		}
	}
	m_head = NULL;
	m_tail = NULL;
	m_size = 0;
}

// **************************************************************************
// 类的四大函数：构造函数、拷贝构造函数、重载赋值运算符、析构函数
// **************************************************************************
Queue::Queue()
{
	m_head = NULL;
	m_tail = NULL;
	m_size = 0;
}

Queue::Queue(const Queue &Queue)
{
	m_head = NULL;
	m_tail = NULL;

	m_size = Queue.m_size;

	if(Queue.m_head){
		Node* tmp = Queue.m_head;
		Node* q = NULL;
		while(tmp){
			Node* node = new Node(tmp->data);
			if(!m_head){
				m_head = node;
				q = m_head;
			}
			else{
				q->next = node;
				q = node;
			}
			tmp = tmp->next;
		}
		m_tail = q; 
	}
	else{
		m_head = NULL;
		m_tail = NULL;
	}
}

Queue& Queue::operator=(const Queue &Queue)
{
	Free();

	m_size = Queue.m_size;

	if(Queue.m_head){
		Node* tmp = Queue.m_head;
		Node* q = NULL;
		while(tmp){
			Node* node = new Node(tmp->data);
			if(!m_head){
				m_head = node;
				q = m_head;
			}
			else{
				q->next = node;
				q = node;
			}

			tmp = tmp->next;
		}
		m_tail = q; 
	}
	else{
		m_head = NULL;
		m_tail = NULL;
	}

	return *this;
}

Queue::~Queue()
{
	if (m_head){
		Node* tmp = m_head;
		while (tmp){
			m_head = m_head->next;
			delete tmp;
			tmp = m_head;
		}
	}
	m_head = NULL;
	m_tail = NULL;
}

// **************************************************************************
// 增删改查
// **************************************************************************
void Queue::Push(const int& data)
{
	Node* tmp = new Node(data);
	if (!m_head) {
		m_head = tmp;
		m_tail = tmp;
	}
	else{
		tmp->next = m_head;
		m_head = tmp;
	}
	++m_size;
}

int Queue::Pop()
{
	assert(m_size > 0);

	int val = 0;
	Node *cur, *pri;
	if (!m_head->next){
		val = m_head->data;
		delete m_head;
		m_head = NULL;
		m_tail = NULL;
		m_size = 0;
	}
	else{
		cur = m_head;
		while (cur->next->next){
			cur = cur->next;
		}
		pri = cur;
		m_tail = cur;
		cur = cur->next;
		pri->next = NULL;
		val = cur->data;
		delete cur;
		cur = NULL;

		--m_size;
	}

	return val;
}

unsigned short Queue::Size()
{
	return m_size;
}

bool Queue::IsEmpty()
{
	return (m_size == 0);
}

void Queue::PrintQueue()
{
	cout << "size : " << m_size << " , content : ";
	if (m_head){
		Node* tmp = m_head;
		while (tmp){
			cout << tmp->data << " -> ";
			tmp = tmp->next;
		}
	}

	cout << "NULL" << endl;
}

// test for Queue
#include "Queue.h"
#include <cstdlib>
#include <iostream>

using namespace std;

int main()
{
	Queue queue;
	for (int i = 1; i < 5; ++i){
		queue.Push(i);
	}
	queue.PrintQueue();

	Queue queueCopy(queue);
	queueCopy.PrintQueue();

	Queue queueAssig;
	queueAssig = queue;
	queueAssig.PrintQueue();

	int pop = queue.Pop();
	cout << "pop:" << pop << endl;
	queue.PrintQueue();

	system("pause");

	return 0;
}