队列C++ | 用数组实现队列_1

用数组实现队列

/* Queue - Circular Array implementation in C++*/
#include<iostream>
using namespace std; 
#define MAX_SIZE 101  //maximum size of the array that will store Queue. 

// Creating a class named Queue.
class Queue
{
private:
	int A[MAX_SIZE];
	int front, rear; 
public:
	// Constructor - set front and rear as -1. 
	// We are assuming that for an empty Queue, both front and rear will be -1.
	Queue()
	{
		front = -1; 
		rear = -1;
	}

	// To check wheter Queue is empty or not
	bool IsEmpty()
	{
		return (front == -1 && rear == -1); 
	}

	// To check whether Queue is full or not
	bool IsFull()
	{
		return (rear+1)%MAX_SIZE == front ? true : false;
	}

	// Inserts an element in queue at rear end
	void Enqueue(int x)
	{
		cout<<"Enqueuing "<<x<<" \n";
		if(IsFull())
		{
			cout<<"Error: Queue is Full\n";
			return;
		}
		if (IsEmpty())
		{ 
			front = rear = 0; 
		}
		else
		{
		    rear = (rear+1)%MAX_SIZE;
		}
		A[rear] = x;
	}

	// Removes an element in Queue from front end. 
	void Dequeue()
	{
		cout<<"Dequeuing \n";
		if(IsEmpty())
		{
			cout<<"Error: Queue is Empty\n";
			return;
		}
		else if(front == rear ) 
		{
			rear = front = -1;
		}
		else
		{
			front = (front+1)%MAX_SIZE;
		}
	}
	// Returns element at front of queue. 
	int Front()
	{
		if(front == -1)
		{
			cout<<"Error: cannot return front from empty queue\n";
			return -1; 
		}
		return A[front];
	}
	/* 
	   Printing the elements in queue from front to rear. 
	   This function is only to test the code. 
	   This is not a standard function for Queue implementation. 
	*/
	void Print()
	{
		// Finding number of elements in queue  
		int count = (rear+MAX_SIZE-front)%MAX_SIZE + 1;
		cout<<"Queue       : ";
		for(int i = 0; i <count; i++)
		{
            // Index of element while travesing 
			int index = (front+i) % MAX_SIZE; circularly from front
			cout<<A[index]<<" ";
		}
		cout<<"\n\n";
	}
};
int main()
{
	/*Driver Code to test the implementation
	  Printing the elements in Queue after each Enqueue or Dequeue 
	*/
   Queue Q; // creating an instance of Queue. 
   Q.Enqueue(2);  Q.Print();  
   Q.Enqueue(4);  Q.Print();  
   Q.Enqueue(6);  Q.Print();
   Q.Dequeue();	  Q.Print();
   Q.Enqueue(8);  Q.Print();
}

---

编程中最没用的东西是源代码，最有用的东西是算法和数据结构。