数据结构——栈和队列之循环队列与链队列

循环队列

代码如下：

#include "pch.h"
#include <iostream>
using namespace std;
#define MAXSIZE 5

struct SqQueue
{
	char* Base;
	int front;
	int rear;
};

//初始化循环队列
int initqueue(SqQueue &q)
{
	q.Base = new char[MAXSIZE];
	if (!q.Base)
	{
		cout << "内存空间分配失败！" << endl;
		return 0;
	}
	q.front = q.rear = 0;
	return 1;
}
//求循环队列的长度
int getqueuelength(SqQueue q)
{
	return (q.rear - q.front + MAXSIZE) % MAXSIZE;
}
//求循环队列的头元素
char getqueuehead(SqQueue q)
{
	return q.Base[q.front];		//q.front 是下标位置
}
//循环队列的入队
int insertqueue(SqQueue &q, char e)
{
	if ((q.rear+1)%MAXSIZE==q.front)//这样队列就满了
	{
		cout << "队列已满，无法继续插入队列！" << endl;
		return 0;
	}
	q.Base[q.rear] = e;
	q.rear = (q.rear + 1) % MAXSIZE;
	cout << "入队列成功！" << endl;
	return 1;
}
//循环队列的出队列
int outputqueue(SqQueue &q, char e)
{
	if (q.rear==q.front)
	{
		cout << "队列为空，无法出队列！" << endl;
		return 0;
	}
	e=q.Base[q.front];
	q.front = (q.front + 1) % MAXSIZE;
	cout << "出队列成功！" << endl;
	return 1;
}
int main()
{
	SqQueue q;
	initqueue(q);
	insertqueue(q, 'a');
	insertqueue(q, 'b');
	insertqueue(q, 'c');
	cout << getqueuehead(q) << endl;;
	char c='a';
	outputqueue(q,c);
	cout << getqueuehead(q) << endl;
	outputqueue(q, c);
	cout << getqueuehead(q) << endl;
	cout << "循环队列的长度为：" << getqueuelength(q) << endl;
	return 0;
}

结果为：

链队列

代码如下：

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

//链队列
typedef struct qnode
{
	char data;
	qnode *next;
}*queueper;

//头指针和尾指针
struct linkqueue
{
	queueper front;		//队列的尾指针
	queueper rear;		//队列的头指针
};
//初始化队列
int initlinkqueue(linkqueue &q)
{
	//创建新节点设置为头，队尾队头志向该节点
	q.front = q.rear = new qnode;
	q.rear->next = NULL;//头结点指针域设置为空
	return 0;
}
//获取队列的头元素
char getqueueHead(linkqueue q)
{
	if (q.front!=q.rear)
	{
		return q.front->next->data;
	}
}
//链队列入队列
int insertelem(linkqueue &q,char e)
{
	queueper p;
	p = new qnode;
	p->data = e;
	p->next = NULL;
	q.rear->next = p;	//将新节点插入到队列的尾部（后插法）
	q.rear = p;			//尾指针指向尾结点
	cout << "队列入队成功！" << endl;
	return 0;
}
//链队列出队列
int outputqueue(linkqueue &q, char &e)
{
	queueper p;
	if (q.rear==q.front)
	{
		cout << "队列为空，无法出队列！" << endl;
		return 0;
	}
	p = q.front->next;		//指向队头元素
	e = p->data;			//得到队头元素的数据域
	q.front->next = p->next;//修改头指针
	if (q.front==p)
	{
		q.rear = q.front;
	}
	delete p;
	cout << "出队列成功！" << endl;
	return 1;
}
int main()
{
	linkqueue q;
	initlinkqueue(q);
	insertelem(q, 'a');
	insertelem(q, 'b');
	insertelem(q, 'c');
	insertelem(q, 'd');
	cout << "队列的头元素为:" << getqueueHead(q) << endl;
	char e = 'a';
	outputqueue(q, e);
	cout << "队列的头元素为:" << getqueueHead(q) << endl; 
	outputqueue(q, e);
	cout << "队列的头元素为:" << getqueueHead(q) << endl;
	return 0;

结果为：