队列——链式存储结构及其基本运算（链队列的另一种表达方式）

问题描述：采用一个不带头结点只有一个尾结点指针rear的循环单链表存储队列，设计出这种链队的进队、出队、判队空和求队中元素个数的算法。 

代码示例：

#include <iostream>using namespace std;template <typename T>struct LinkNode//链队数据结点类型{T data;//结点数据域LinkNode *next;//指向下一个结点};template <typename T>class LinkQueueClass2{LinkNode<T> *rear;//链队队尾指针public:LinkQueueClass2();//构造函数,用于队列初始化~LinkQueueClass2();//析构函数,用于释放队列空间bool QueueEmpty();//判队空运算算法void enQueue(T e);//进队运算算法bool deQueue(T &e);//出队运算算法int GetCount();//求链队中元素个数};template <typename T>LinkQueueClass2<T>::LinkQueueClass2()//构造函数,用于队列初始化{rear = NULL;}template <typename T>LinkQueueClass2<T>::~LinkQueueClass2()//析构函数,用于释放队列空间{LinkNode<T> *pre = rear, *p;if (rear == NULL) return;p = pre->next;while (p != rear){delete pre;pre = p; p = p->next;}delete pre;}template <typename T>bool LinkQueueClass2<T>::QueueEmpty()//判队空运算算法{return (rear == NULL);}template <typename T>void LinkQueueClass2<T>::enQueue(T e)//进队运算算法{LinkNode<T> *p;p = new LinkNode<T>();p->data = e;if (rear == NULL){p->next = p;rear = p;}else{p->next = rear->next;rear->next = p;rear = p;}}template <typename T>bool LinkQueueClass2<T>::deQueue(T &e)//出队运算算法{LinkNode<T> *q;if (rear == NULL)return false;else if (rear->next == rear){e = rear->data;delete rear;rear = NULL;}else{q = rear->next;e = q->data;rear->next = q->next;delete q;}return true;}template <typename T>int LinkQueueClass2<T>::GetCount()//求链队中元素个数{LinkNode<T> *p = rear;if (rear == NULL)return 0;p = rear->next;int i = 1;while (p != rear){i++;p = p->next;}return i;}//===main函数用作调试void main(){LinkQueueClass2<char> lq;//定义一个字符链队lqchar e;cout << "建立一个空队lq\n";cout << "队lq" << (lq.QueueEmpty() ? "空" : "不空") << endl;cout << "元素a进队\n"; lq.enQueue('a');cout << "元素b进队\n"; lq.enQueue('b');cout << "元素c进队\n"; lq.enQueue('c');cout << "元素d进队\n"; lq.enQueue('d');cout << "元素e进队\n"; lq.enQueue('e');cout << "队lq" << (lq.QueueEmpty() ? "空" : "不空") << endl;cout << "所有元素出队次序:";while (!lq.QueueEmpty())//队不空循环{lq.deQueue(e);//出队元素ecout << e << " ";//输出元素e}cout << endl;cout << "销毁队lq" << endl;}