栈 队列 数据结构用两个栈实现一个队列的实例

#include <iostream>
using namespace std;
#include <stack>
#include <stdlib.h>

template <class T>
class SQueue {
public:
  void Push(const T& value);
  T Pop();
private:
  stack<T> st1;
  stack<T> st2;
};

template <class T>
T SQueue<T>::Pop()
{
  if (st2.size() <= 0)
  {
    if (st1.size() == 0)
    {
      exit(1);
    }
    while ((st1.size() > 0))
    {
      T& top = st1.top();
      st2.push(top);
      st1.pop();
    }
  }

  T head = st2.top();
  st2.pop();
  return head;

}

template <class T>
void SQueue<T>::Push(const T& value)
{
  st1.push(value);
}

int main()
{
  SQueue<int> sq;
  for (int i = 0; i < 10; ++i)
  {
    sq.Push(i);
  }
  for (int i = 0; i < 5; ++i) 
  {
    cout << sq.Pop() << " ";
  }

  for (int i = 0; i < 5; ++i) //分两次验证
  {
    cout << sq.Pop() << " ";
  }
  cout << endl;

  system("pause");
  return 0;
}