queue.cpp

#include <iostream>

using namespace std;

struct Node{
	int x;
	Node *right;
	Node *left;

	Node(int a){
		x = a;
		this->left = NULL;
		this->right = NULL;
	}

};

// 1
struct Queue
{

	Node *first;
	Node *last;

	Queue(){

		this->first = NULL;
		this->last = NULL;
	}

	void push(int x){

		Node *node = new Node(x);
		
		node->right = this->first;
		if(this->first != NULL){
			this->first->left = node;
		}

		this->first = node;

		if(this->last == NULL){
			this->last = node;
		}


	}

	//123
	void pop(){

		if(this->last == NULL || this->first == NULL){
			cout << "Danh sach rong" << endl;
			return;
		}

		this->last = this->last->left;
		delete[] this->last;

		if(this->last != NULL){
			this->last->right = NULL;
		}

	}

	void output(){

		if(this->first == NULL){
			cout << "Queue is empty." << endl;
			return;
		}

		cout << "Queue:" ;
		Node *node = this->first;

		while(node != NULL){
			cout << node->x << ", ";
			node = node->right;
		}

	}


};



int main()
{
	
	Queue q;

	//123 -> sieu thi
	q.push(3);
	q.push(2);
	q.push(1);


	q.output();

	cout << "Bat dau xoa" << endl;
	q.pop();
	q.pop();
	q.pop();
	q.output();



	return 0;
}