顺序队列

Posted 2021-03-02 wind-flies

目录

• Queue_head.h
• main.cpp

Queue_head.h

#ifndef _Queue_head_H
#define _Queue_head_H

#include <iostream>
template <typename T>
class Queue
{
public:
	Queue(int queueCapacity=10);
	bool IsEmpty() const;
	T& Front() const; 		  // 查看队首数据
	T& Rear() const;  		  // 查看队尾数据
	void Push(const T& item); // 队尾压入数据
	void Pop(); 			  // 队首删除数据

private:
	T* queue;
	int front; 	  // 队首位置
	int rear;     // 队尾位置
	int capacity; // 容量
	
};

template <typename T>
Queue<T>::Queue(int queueCapacity):capacity(queueCapacity)
{
	if(capacity < 1) throw "Queue capacity must be > 0";
	queue = new T[capacity];
	front = rear = 0; // 初始
}

template <typename T>
inline bool Queue<T>::IsEmpty() const
{
	return front == rear;
}

template <typename T>
void Queue<T>::Push(const T& item)
{
	if((rear+1) % capacity == front) // 判断队列满了吗
	{
		// 加倍
		T* newQueue = new T[2*capacity - 1];

		int start = (front+1) % capacity;
		if(start < 2) // 没有回绕
			std::copy(queue+start, queue+start+capacity-1, newQueue);
		else{
			std::copy(queue+start, queue+capacity, newQueue);
			std::copy(queue, queue+rear+1, newQueue+capacity-start);
		}
		front = 2 * capacity - 1;
		rear  = capacity - 2;
		capacity *= 2;
		delete[] queue;
		queue = newQueue;

	}
	// if (rear == capacity-1){
	// 	rear = 0;
	// }
	// else
	// 	// 队首空的
	// 	rear ++;
	rear = (rear+1) % capacity; // 相当于if else 的作用
	queue[rear] = item;
}

template <typename T>
inline T& Queue<T>::Front() const
{
	if(IsEmpty()) throw "No front element";
	return queue[(front+1) % capacity]; // 队首一直是空的
										// 取余处理回绕
}

template <typename T>
inline T& Queue<T>::Rear() const
{
	if(IsEmpty()) throw "No rear element";
	return queue[rear];
}

template <typename T>
void Queue<T>::Pop() // 删除队首数据
{
	if(IsEmpty()) throw "cannot delete";
	front = (front + 1) % capacity; // 处理回绕
	queue[front].~T();
}

#endif

main.cpp

/*
* author:起风了_Zoe
* date:2020.04.07
*/

#include <iostream>
#include "Queue_head.h"
using namespace std;

int main()
{
	Queue<char> q(4);
	q.Push(‘a‘);q.Push(‘b‘);q.Push(‘c‘);
	cout << q.Front() << "|" << q.Rear() << endl;
	q.Push(‘d‘);q.Push(‘e‘);q.Push(‘f‘);
	q.Push(‘g‘);q.Push(‘h‘);q.Push(‘i‘);
	cout << q.Front() << "|" << q.Rear() << endl;
	cout << "OK!!!" <<endl;
	return 0;
}