【练习3.25】
编写实现队列的例程，使用
a.链表
b.数组
Answer:
在这章一开头就已经写了个链表的队列例程了，所以实际上只要做b小题就可以。
数组模拟队列和链表的两点小不同是：
①、数组空间有限，入队需要检测数组是否已经满
②、数组经过几次操作后，rear可能绕回front前面，所以许多操作都要用模来实现。
测试代码：
1 #include <iostream> 2 #include "queue.h" 3 using namespace std; 4 using namespace queue; 5 template class Queue<int>; 6 int main(void) 7 { 8 Simu_Queue<int> test(6); 9 //测试插入 10 test.enqueue(2); 11 test.enqueue(3); 12 test.enqueue(5); 13 test.enqueue(7); 14 test.enqueue(11); 15 test.enqueue(13); 16 test.enqueue(17); 17 test.traverse(); 18 cout << endl; 19 //测试删除 20 test.dequeue(); 21 test.dequeue(); 22 test.dequeue(); 23 test.traverse(); 24 cout << endl; 25 //测试绕数组遍历 26 test.enqueue(17); 27 test.enqueue(19); 28 test.enqueue(23); 29 test.traverse(); 30 cout << endl; 31 32 system("pause"); 33 }
实现代码：
1 //练习3.25新增，用数组模拟队列 2 template <typename T> class Simu_Queue 3 { 4 public: 5 Simu_Queue() :head(nullptr), front(0), rear(0), size(0){} 6 Simu_Queue(unsigned int _maxsize) :front(0), rear(0), maxsize(_maxsize){ head = new T[maxsize + 1]; } 7 Simu_Queue(const Simu_Queue& another) 8 { 9 front = another.front; 10 rear = another.rear; 11 maxsize = another.maxsize; 12 head = new T[maxsize + 1]; 13 for (unsigned i = 0; i < maxsize + 1; ++i) 14 head[i] = another.head[i]; 15 } 16 ~Simu_Queue() 17 { 18 delete[] head; 19 front = rear = maxsize = 0; 20 head = nullptr; 21 } 22 Simu_Queue& operator=(const Simu_Queue& another) 23 { 24 if (this != &another) 25 { 26 delete[] head; 27 front = another.front; 28 rear = another.rear; 29 maxsize = another.maxsize; 30 head = new T[maxsize + 1]; 31 for (unsigned i = 0; i < maxsize + 1; ++i) 32 head[i] = another.head[i]; 33 } 34 } 35 public: 36 //返回最大元素量 37 unsigned int size()const{ return maxsize; } 38 //返回当前元素量 39 unsigned int length()const{ return front <= rear ? rear - front : rear + maxsize + 1 - front; } 40 //判断是否为空 41 bool empty()const{ return front == rear; } 42 //入队 43 bool enqueue(const T &item) 44 { 45 if ((rear + 1) % (maxsize + 1) != front) 46 { 47 head[rear] = item; 48 rear = (rear + 1) % (maxsize + 1); 49 return true; 50 } 51 return false; 52 } 53 //出队 54 bool dequeue() 55 { 56 if (rear != front) 57 { 58 front = (front + 1) % (maxsize + 1); 59 return true; 60 } 61 return false; 62 } 63 //输出队列元素 64 void traverse()const 65 { 66 unsigned int temp = front; 67 while (temp != rear) 68 { 69 cout << " " << head[temp] << flush; 70 temp = (temp + 1) % (maxsize + 1); 71 } 72 } 73 private: 74 T* head = nullptr; 75 unsigned int front; 76 unsigned int rear; 77 unsigned int maxsize; 78 };