顺序队列c++

通过数组建立队列

  1 #include <iostream>
  2 
  3 using namespace std;
  4 
  5 template<class T>
  6 class MyQueue
  7 {
  8 public:
  9     MyQueue(int queuecapacity=10);
 10     ~MyQueue();
 11 
 12     bool IsEmpty() const;
 13     T& Front() const;
 14     T& Rear() const;
 15     void Push(const T& item);
 16     void Pop();
 17 private:
 18     T *Queue;
 19     int myfront;
 20     int myrear;
 21     int capacity;
 22 };
 23 template<class T>
 24 inline MyQueue<T>::MyQueue(int queuecapacity):capacity(queuecapacity)
 25 {
 26     if(capacity<1) throw "capacity must be > 0";
 27     Queue = new T[capacity];
 28     myfront = myrear = 0;
 29 }
 30 
 31 template<class T>
 32 MyQueue<T>::~MyQueue()
 33 {
 34     delete[] Queue;
 35 }
 36 
 37 template<class T>
 38 bool MyQueue<T>::IsEmpty() const
 39 {
 40     return myfront==myrear;
 41 }
 42 
 43 template<class T>
 44 T& MyQueue<T>::Front() const
 45 {
 46     if(IsEmpty()) throw "Queue is empty";
 47     return Queue[(myfront+1) % capacity];
 48 }
 49 
 50 template<class T>
 51 T& MyQueue<T>::Rear() const
 52 {
 53     if(IsEmpty()) throw "Queue is empty";
 54     return Queue[myrear];
 55 }
 56 
 57 template<class T>
 58 void MyQueue<T>::Push(const T& item)
 59 {
 60     if((myrear+1)%capacity==myfront)
 61     {
 62         T* newQueue = new T[2*capacity];
 63         int start = (myfront+1)%capacity;
 64         if(start<2)
 65         {
 66             copy(Queue+start,Queue+start+capacity-1,newQueue);
 67         }
 68         else
 69         {
 70             copy(Queue+start,Queue+capacity,newQueue);
 71             copy(Queue,Queue+myrear+1,newQueue+capacity-start);
 72         }
 73         myfront = 2*capacity-1;
 74         myrear = capacity-2;
 75         capacity *= 2;
 76         delete[] Queue;
 77         Queue = newQueue;
 78     }
 79     myrear = (myrear+1) % capacity;
 80     Queue[myrear] = item;
 81 }
 82 
 83 template<class T>
 84 void MyQueue<T>::Pop()
 85 {
 86     if(IsEmpty()) throw "Queue is empty";
 87     myfront = (myfront+1) % capacity;
 88     Queue[myfront].~T(); // 某课程上说这样写很厉害
 89 }
 90 
 91 int main()
 92 {
 93     MyQueue<char> a(10);
 94     a.Push('A');
 95     a.Push('B');
 96     a.Push('C');
 97     a.Push('D');
 98     cout << a.Front() << endl;
 99     cout << a.Rear() << endl;
100     a.Pop();
101     a.Pop();
102     cout << a.Front() << endl;
103     cout << "Hello world!" << endl;
104     return 0;
105 }

 

posted @ 2020-03-14 19:46  yg_staring  阅读(250)  评论(0)  编辑  收藏  举报