template<typename Y>用两个queue实现stack

题目名称 : [Template]Review Template and Stack (eden)

时间限制 : 1000 ms

空间限制 : 32 MB

Description

**key points: **

template class and function, stack and queue.

Description:

In this assignment, you need to complete Class Stack's declaration and definition with Template. The different thing is that the Stack is implemented by two queues. Following is the example of Stack in integer:

class Stack {  public:    Stack(); // constructor.    void push(const int& data); // push operation.    int pop(); // return the value in the top and pop it out of the stack.    int top(); // return the value in top.    int size() const;  // return size of the stack.    bool empty(); // check whether is empty.  private:    queue<int> q1; // two queues.    queue<int> q2;    int count; // the number of elements.};

And you need to define a print function to print the content in the Stack from top to bottom. The format is: every element is followed by a blank space and an endl in the end.

Extra:

1. You are not allowed to use any STL except "queue".

2. For more detail, see the codes in main.cpp.

代码：

Stack.h:

#include <queue>
#include <iostream>


using namespace std;


template <typename T>
class Stack
{
public:
Stack();
void push(const T& data);
T pop();
T top();
int size() const;
bool empty();
private:
queue<T> q1;
queue<T> q2;
int count;
};


template<typename T>
Stack<T>::Stack()
{
count = 0;
}
template<typename T>
int Stack<T>::size() const
{
return count;
}
template<typename T>
bool Stack<T>::empty()
{
return count == 0;
}
template<typename T>
void Stack<T>::push(const T& data)
{
if((q1.empty() && q2.empty()) || (!q1.empty()))
{
q1.push(data);
}
else if(!q2.empty())
{
q2.push(data);
}
count++;
}
template<typename T>
T Stack<T>::pop()
{
if(!empty())
{
if(q2.empty())
{
T value = q1.back();
int size = q1.size() - 1;
while(size--)
{
q2.push(q1.front());
q1.pop();
}
q1.pop();
   count--;
   return value;
}
else if(q1.empty())
{
T value = q2.back();
int size = q2.size() - 1;
while(size--)
{
q1.push(q2.front());
q2.pop();
}
q2.pop();
   count--;
   return value;
}
}

}
template<typename T>
T Stack<T>::top()
{
if(!q1.empty())
{
return q1.back();
}
else return q2.back();
}
template<typename T>
void print(Stack<T> stack)
{
while(!stack.empty()) 
{
cout<<stack.top()<<" ";
stack.pop();
}
cout<<endl;
}

main.cpp:

#include "Stack.h"
#include<iostream>
#include<exception>


using namespace std;


class StackForbidden : public exception {
    virtual const char *what() const throw() {
        return "Please do not use Stack in stl..";
    }
};


int main() {


    #if defined(_GLIBCXX_STACK)
        throw StackForbidden();
    #endif


    Stack<int> stack;
    stack.push(88);
    stack.push(44);
    stack.push(99);
    cout << "The size is: " << stack.size() << endl;
    if (!stack.empty()) cout << stack.top() << endl;
    print(stack);


    stack.pop();
    print(stack);


    stack.push(777);
    cout << "The size is: " << stack.size() << endl;
    if (!stack.empty()) cout << stack.top() << endl;
    print(stack);


    stack.pop();
    stack.pop();
    cout << "The size is: " << stack.size() << endl;
    print(stack);
    stack.pop();
    if (!stack.empty()) cout << stack.top() << endl;
    else cout << "it is empty now." << endl;


    Stack<double> stack1;
    int n, m;
    cin >> n >> m;
    for (int i = 0; i < n; i++) {
        stack1.push(i + 0.01);
    }
    print(stack1);
    while (m--) {
        stack1.pop();
    }
    cout << "The size is: " << stack1.size() << endl;
    if (!stack1.empty()) cout << stack1.top() << endl;
    print(stack1);


}

知识点1：

/*如果q1与q2都为空，那么往q1中插入元素
如果q1不为空，那么往q1中插入元素
如果q2不为空，那么往q1中插入元素
*/

知识点2：

/*在template<typename Y>和template<class Y>中， 
typename和class的意义完全一样。*/