【栈，队列】两队列实现栈
一、用STL的queue实现
MyStack.h
#ifndef MYSTACK_H
#define MYSTACK_H
#include<iostream>
#include<queue>
//MyStack
template<typename T>
class MyStack{
public:
typedef T value_type;
typedef T& reference;
MyStack();//constructor
~MyStack();//destructor
void push(const T value);//push
void pop();//pop
reference get_top();//top
bool empty();//whether MyStack is empty or not
int size();//get length
private:
std::queue<T> que1;
std::queue<T> que2;
};
//constructor
template<typename T>
MyStack<T>::MyStack(){}
//destructor
template<typename T>
MyStack<T>::~MyStack(){}
//push
template<typename T>
void MyStack<T>::push(const T value){
if (empty())
que1.push(value);
else if (que1.empty())
que2.push(value);
else if (que2.empty())
que1.push(value);
}
//pop
template<typename T>
void MyStack<T>::pop(){
if (empty()){
std::cout << "there is no element in stack" << std::endl;
exit(1);
}else if (que1.empty()){
while (que2.size() > 1){
value_type data = que2.front();
que1.push(data);
que2.pop();
}
que2.pop();
}else if (que2.empty()){
while (que1.size()>1){
value_type data = que1.front();
que2.push(data);
que1.pop();
}
que1.pop();
}
}
//top
template<typename T>
typename MyStack<T>::reference MyStack<T>::get_top(){
if (empty()){
std::cout << "there is no element in stack" << std::endl;
exit(1);
}
else if (que1.empty()){
return que2.back();
}
else if (que2.empty()){
return que1.back();
}
}
//whether MyStack is empty or not
template<typename T>
bool MyStack<T>::empty(){
return size() == 0 ? true : false;
}
//get length
template<typename T>
int MyStack<T>::size(){
return que1.size() + que2.size();
}
#endif
main.cpp
#include"MyStack.h"
using namespace std;
int main(){
MyStack<int> int_stack;
cout << int_stack.size() << endl; //0
cout << boolalpha << int_stack.empty() << endl;//true
int_stack.push(1);
cout << int_stack.size() << endl; //1
cout << int_stack.get_top() << endl;//1
int_stack.pop();
for (int i = 0; i < 20; i++){
int_stack.push(i);
}
cout << int_stack.size() << endl; //20
cout << int_stack.get_top() << endl;//19
cout << boolalpha << int_stack.empty() << endl;//false
int_stack.push(21);
cout << int_stack.get_top() << endl;//21
int_stack.pop();
cout << int_stack.get_top() << endl;//19
int_stack.pop();
int_stack.push(22);
cout << int_stack.size() << endl; //20
cout << int_stack.get_top() << endl;//22
int_stack.pop();
cout << int_stack.get_top() << endl;//18
return 0;
}
二、用自己写的LinkedQueue实现
LinkedQueue.h
#ifndef LINKEDQUEUE_H
#define LINKEDQUEUE_h
#include<iostream>
//queue node
template<typename T>
struct queue_node{
typedef queue_node<T>* pointer;
T data;
pointer next;
queue_node() :next(NULL){}
queue_node(const T value) :data(value), next(NULL){}
};
//LinkedQueue
template<typename T>
class LinkedQueue{
public:
typedef T value_type;
typedef T* pointer;
typedef T& reference;
typedef queue_node<T>* linked_type;
LinkedQueue();//constructor
~LinkedQueue();//destructor
void push(const T value);//push
void pop();//pop
reference get_front();//front
reference get_back();//back
bool empty();//whether LinkedQueue is empty or not
int size();//get length
private:
void clear();//clear LinkedQueue
private:
linked_type front;
linked_type rear;
};
//constructor
template<typename T>
LinkedQueue<T>::LinkedQueue() :front(new queue_node<T>()), rear(front){}
//destructor
template<typename T>
LinkedQueue<T>::~LinkedQueue(){
clear();
delete front;
front = NULL;
rear = NULL;
}
//push
template<typename T>
void LinkedQueue<T>::push(const T value){
linked_type p = new queue_node<T>(value);
rear->next = p;
rear = p;
}
//pop
template<typename T>
void LinkedQueue<T>::pop(){
if (empty()){
std::cout << "there is no element in queue" << std::endl;
exit(1);
}
linked_type p = front->next;
front->next = p->next;
if (rear == p)
rear = front;
delete p;
}
//front
template<typename T>
typename LinkedQueue<T>::reference LinkedQueue<T>::get_front(){
if (empty()){
std::cout << "there is no element in queue" << std::endl;
exit(1);
}
return front->next->data;
}
//back
template<typename T>
typename LinkedQueue<T>::reference LinkedQueue<T>::get_back(){
if (empty()){
std::cout << "there is no element in queue" << std::endl;
exit(1);
}
return rear->data;
}
//whether LinkedQueue is empty or not
template<typename T>
bool LinkedQueue<T>::empty(){
return front == rear ? true : false;
}
//get length
template<typename T>
int LinkedQueue<T>::size(){
int count = 0;
linked_type p = front->next;
while (p != NULL){
p = p->next;
count++;
}
return count;
}
//clear LinkedQueue
template<typename T>
void LinkedQueue<T>::clear(){
rear = front;
linked_type p = front->next;
linked_type q;
front->next = NULL;
while (p != NULL){
q = p;
p = p->next;
delete q;
}
}
#endif
MyStack.h
#ifndef MYSTACK_H
#define MYSTACK_H
#include"LinkedQueue.h"
#include<iostream>
//MyStack
template<typename T>
class MyStack{
public:
typedef T value_type;
typedef T& reference;
MyStack();//constructor
~MyStack();//destructor
void push(const T value);//push
void pop();//pop
reference get_top();//top
bool empty();//whether MyStack is empty or not
int size();//get length
private:
LinkedQueue<T> que1;
LinkedQueue<T> que2;
};
//constructor
template<typename T>
MyStack<T>::MyStack(){}
//destructor
template<typename T>
MyStack<T>::~MyStack(){}
//push
template<typename T>
void MyStack<T>::push(const T value){
if (empty())
que1.push(value);
else if (que1.empty())
que2.push(value);
else if (que2.empty())
que1.push(value);
}
//pop
template<typename T>
void MyStack<T>::pop(){
if (empty()){
std::cout << "there is no element in stack" << std::endl;
exit(1);
}
else if (que1.empty()){
while (que2.size() > 1){
value_type data = que2.get_front();
que1.push(data);
que2.pop();
}
que2.pop();
}
else if (que2.empty()){
while (que1.size()>1){
value_type data = que1.get_front();
que2.push(data);
que1.pop();
}
que1.pop();
}
}
//top
template<typename T>
typename MyStack<T>::reference MyStack<T>::get_top(){
if (empty()){
std::cout << "there is no element in stack" << std::endl;
exit(1);
}
else if (que1.empty()){
return que2.get_back();
}
else if (que2.empty()){
return que1.get_back();
}
}
//whether MyStack is empty or not
template<typename T>
bool MyStack<T>::empty(){
return size() == 0 ? true : false;
}
//get length
template<typename T>
int MyStack<T>::size(){
return que1.size() + que2.size();
}
#endif
main.cpp
#include"MyStack.h"
using namespace std;
int main(){
MyStack<int> int_stack;
cout << int_stack.size() << endl; //0
cout << boolalpha << int_stack.empty() << endl;//true
int_stack.push(1);
cout << int_stack.size() << endl; //1
cout << int_stack.get_top() << endl;//1
int_stack.pop();
for (int i = 0; i < 20; i++){
int_stack.push(i);
}
cout << int_stack.size() << endl; //20
cout << int_stack.get_top() << endl;//19
cout << boolalpha << int_stack.empty() << endl;//false
int_stack.push(21);
cout << int_stack.get_top() << endl;//21
int_stack.pop();
cout << int_stack.get_top() << endl;//19
int_stack.pop();
int_stack.push(22);
cout << int_stack.size() << endl; //20
cout << int_stack.get_top() << endl;//22
int_stack.pop();
cout << int_stack.get_top() << endl;//18
return 0;
}