队列-线性实现：循环队列

 1 //
 2 // Created by geshenglu on 2020/4/14.
 3 //
 4 
 5 #ifndef SEQQUEUE_QUEUE_H
 6 #define SEQQUEUE_QUEUE_H
 7 template <class T>
 8 class Queue{
 9 public:
10     virtual bool IsEmpty() const =0;
11     virtual void EnQueue(const T&x)=0;
12     virtual T DeQueue() =0;
13     virtual T GetHead()const =0;
14     virtual ~Queue() {};
15 };
16 
17 #endif //SEQQUEUE_QUEUE_H

 1 //
 2 // Created by geshenglu on 2020/4/14.
 3 //
 4 
 5 #ifndef SEQQUEUE_SEQQUEUE_H
 6 #define SEQQUEUE_SEQQUEUE_H
 7 #include "Queue.h"
 8 #include <iostream>
 9 template <typename T>
10 class SeqQueue :public Queue<T>{
11 private:
12     T *elem;
13     int maxSize;
14     int front,rear;
15     void doubleSize();
16 
17 public:
18     SeqQueue(int size=10);
19     ~SeqQueue();
20     virtual bool IsEmpty() const override ;
21     virtual void EnQueue(const T&x)override ;
22     virtual T DeQueue() override ;
23     virtual T GetHead()const override ;
24     void ShowQueue()const;
25 };
26 
27 template <typename T>
28 void SeqQueue<T>::ShowQueue() const
29 {
30     for (int i=front+1;i<=rear;++i)
31     {
32         std::cout << elem[i] << ' ';
33     }
34     std::cout << std::endl;
35 }
36 
37 template <typename T>
38 SeqQueue<T>::SeqQueue(int size) {
39     maxSize = size;
40     elem = new T[maxSize];
41     front = rear = 0;
42 }
43 
44 template <typename T>
45 SeqQueue<T>::~SeqQueue() {
46     delete[]elem;
47 }
48 
49 template <typename T>
50 void SeqQueue<T>::doubleSize() {
51     T* tmp = elem;
52     std::cout<<"扩展之前:";
53     ShowQueue();
54     elem = new T[maxSize * 2];
55     for (int i = 1; i < maxSize; ++i)
56         elem[i] = tmp[(front + i)%maxSize];
57     front = 0;
58     rear = maxSize-1;
59     maxSize *= 2;
60     delete tmp;
61 }
62 
63 template <typename T>
64 bool SeqQueue<T>::IsEmpty() const {
65     return front == rear;
66 }
67 
68 template <typename T>
69 void SeqQueue<T>::EnQueue(const T& x) {
70     if ((rear + 1) % maxSize == front)
71         doubleSize();
72     rear = (rear+1) % maxSize;
73     elem[rear] = x;
74 }
75 
76 template <typename T>
77 T SeqQueue<T>::DeQueue() {
78     front = (front + 1) % maxSize;
79     return elem[front];
80 }
81 
82 template <typename T>
83 T SeqQueue<T>::GetHead()const {
84     return elem[(front + 1) % maxSize];
85 }
86 #endif //SEQQUEUE_SEQQUEUE_H

 1 #include <iostream>
 2 #include "SeqQueue.h"
 3 int main() {
 4     SeqQueue<int> queue(10);
 5     queue.EnQueue(12);
 6     queue.EnQueue(13);
 7     queue.EnQueue(14);
 8     queue.EnQueue(15);
 9     queue.EnQueue(16);
10     std::cout <<"队头"<< queue.GetHead() << std::endl;
11     queue.ShowQueue();
12     queue.DeQueue();
13     queue.ShowQueue();
14     queue.EnQueue(999);
15     std::cout << "队头" << queue.GetHead() << std::endl;
16     queue.ShowQueue();
17     return 0;
18 }