Description

A queue is an abstract data type that serves as a collection of elements, where nodes are removed only from the head of the queue and are inserted only at the tail of the queue. Two principal operations can be used to manipulate a queue: enqueue, which inserts an element at the tail, and dequeue, which removes the element at the head of the collection.

 

And now yod need to do the additional command  "empty" , that means you need to empty the queue

Let’s see how the queue data structure can be realized in C++.We have an approach to implement queue: linked list. Thus, we define a class as follows:

 class List_queue {

    public:

        List_queue();

        ~List_queue();

        void enqueue(const int &);

        void dequeue();

        void print();

        void emptys();

    private:

        ListNode *head;

        ListNode *tail;

};

where List_queue implements the queue data structure.

REQUIREMENTS:

Implement the constructor, destructor, enqueue(), dequeue() and print() member functions of the List_queue class.

Note:

1.This problem involves three files.

• function.h: Class definitions.
• function.cpp: Member-function definitions.
• main.cpp: A driver program to test your class implementation.

You will be provided with main.cpp and function.h, and asked to implement function.cpp.

function.h

#ifndef FUNCTION_H #define FUNCTION_H #include <iostream> class ListNode { friend class List_queue; //make List_queue a friend public: ListNode( const int &info ) //constructor : data( info ), nextPtr( NULL ), prevPtr( NULL ) { } //end ListNode constructor private: int data; //data ListNode *nextPtr; // next node in list ListNode *prevPtr; }; //end class ListNode class List_queue { public: List_queue(); ~List_queue(); void enqueue(const int &); void dequeue(); void print(); void emptys(); private: ListNode *head; ListNode *tail; }; #endif

main.cpp

int main(){ List_queue L_queue; char command[10]; int n; while(cin>>command){ if(strcmp(command,"dequeue")==0){ L_queue.dequeue(); }else if(strcmp(command,"enqueue")==0){ cin >> n; L_queue.enqueue(n); } else if (strcmp(command , "empty") == 0){ L_queue.emptys() ; }else if(strcmp(command, "print") == 0){ L_queue.print(); cout << endl; } } return 0; }

2.For OJ submission:

       Step 1. Submit only your function.cpp into the submission block.

       Step 2. Check the results and debug your program if necessary.

 

Input

 

There are three kinds of commands:

• “enqueue integerA” represents inserting an element with int value A at the tail of the queue.
• “dequeue” represents removing the element at the head of the queue.
• “print” represents showing the current content of the queue.
• “empty” represents empty the queue

Each command is followed by a new line character.

Input terminated by EOF.

Output

The output should consist of the current state of the queue.

When the queue is empty, you don’t need to print anything except a new line character.

Sample Input  Download

Sample Output  Download

Partial Judge Code

11946.cpp

Partial Judge Header

11946.h

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