数据结构与算法学习之队列及队列的相关操作

队列也是一张表，它是一种插入操作在一端删除操作在另一端进行的表。队列的操作主要要抓住两个核心位置队头front和队尾rear。队列的主要操作就是入队与出队了。同样，队列也可以使用数组和链表两种方式实现。

下面是本人在学习队列操作时利用链表方式实现的代码：

/***************************************************************************/ /*********************队列的非顺序存储结构实现(链表实现)**********************/ /*********************Shanghai Jiaotong EE zhouguiyin***********************/ #include <iostream> using namespace std; typedef int Elemtype; class Queueitem { public: Elemtype data; Queueitem *next; }; class Queue { public: Queue(); //构造函数初始化一个带有头结点空队列 ~Queue(); void Isempty(); void Print(); void Qinsert(Elemtype); Elemtype Qdelete(); Elemtype Getfront(); private: Queueitem *front; //队头指针 Queueitem *rear; //队尾指针 }; Queue::Queue() { Queueitem *p = new Queueitem; p->next=NULL; front=rear=p; } Queue::~Queue() { Queueitem *sp = front->next; while(rear!=sp) { front->next=sp->next; delete sp; sp=front->next; } delete rear; //删除队尾节点 delete front; //删除头节点 rear=front=NULL; } void Queue::Isempty() { if (front==rear) cout<<"The queue is empty!"<<endl; else cout<<"The queue is non-empty!"<<endl; } void Queue::Print() { Queueitem *iter = front->next; if (front==rear) cout<<"There is no element for printing!"<<endl; else { do { cout<<iter->data<<endl; iter=iter->next; }while(iter!=NULL); } } void Queue::Qinsert(Elemtype x) { Queueitem *p = new Queueitem; p->data=x; p->next=NULL; rear->next=p; rear=p; } Elemtype Queue::Qdelete() { Elemtype x; if (front==rear) cout<<"The queue is empty and can not delete!"<<endl; else { Queueitem *p = front->next; front->next=p->next; if(p->next==NULL) //重要！！当删除最后一个元素时，别把rear误删了 rear=front; x=p->data; delete p; } return x; } Elemtype Queue::Getfront() { if (front == rear) { cout<<"There is no element to get!"<<endl; return 0; } else return front->next->data; } int main() { Queue q; q.Isempty(); q.Qinsert(1); q.Qinsert(3); q.Qinsert(5); q.Qinsert(9); q.Isempty(); q.Print(); Elemtype x = q.Getfront(); cout<<x<<endl; Elemtype y = q.Qdelete(); cout<<y<<endl; Elemtype z = q.Qdelete(); cout<<z<<endl; q.Print(); }