数据结构练习（16）用两个栈实现队列

http://zhedahht.blog.163.com/blog/static/2541117420073293950662/

#include <stack>
#include <cassert>
using namespace std;

template <typename T> class CQueue 
{
public:
    CQueue() {}
    ~CQueue() {}

    void append_tail(const T& element);
    void delete_head();

private:
    stack<T> m_stack1;
    stack<T> m_stack2;
};

template <typename T> void CQueue<T>::append_tail(const T& element)
{
    m_stack1.push(element);
}

template <typename T> void CQueue<T>::delete_head()
{
    if (m_stack2.size() <= 0)
    {
        while (m_stack1.size())
        {
            m_stack2.push(m_stack1.top());
            m_stack1.pop();
        }
    }
    assert(m_stack2.size() > 0);
    m_stack2.pop();
}

int main()
{
    CQueue<int> q;
    q.append_tail(10);
    q.delete_head();
    return 0;
}