剑指offer——面试题9：用两个栈实现队列

#include "Queue.h"

// ====================测试代码====================
void Test(char actual, char expected)
{
    if(actual == expected)
        printf("Test passed.\n");
    else
        printf("Test failed.\n");
}

int main(int argc, char* argv[])
{
    CQueue<char> queue;

    queue.appendTail('a');
    queue.appendTail('b');
    queue.appendTail('c');

    char head = queue.deleteHead();
    Test(head, 'a');

    head = queue.deleteHead();
    Test(head, 'b');

    queue.appendTail('d');
    head = queue.deleteHead();
    Test(head, 'c');

    queue.appendTail('e');
    head = queue.deleteHead();
    Test(head, 'd');

    head = queue.deleteHead();
    Test(head, 'e');

    return ;
}

QueueWithTwoStacks.cpp

 // 面试题9：用两个栈实现队列
 // 题目：用两个栈实现一个队列。队列的声明如下，请实现它的两个函数appendTail
 // 和deleteHead，分别完成在队列尾部插入结点和在队列头部删除结点的功能。

 #pragma once
 #include <stack>
 #include <exception>
 #include<stdio.h>
 #include<stdexcept>

 using namespace std;

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

     // 在队列末尾添加一个结点
     void appendTail(const T& node);

     // 删除队列的头结点
     T deleteHead();

 private:
     stack<T> stack1;
     stack<T> stack2;
 };

 template <typename T> CQueue<T>::CQueue(void)
 {
 }

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

 template<typename T> void CQueue<T>::appendTail(const T& element)
 {
     stack1.push(element);
 }

 template<typename T> T CQueue<T>::deleteHead()
 {
     if(stack2.size()<= )
     {
         while(stack1.size()>)
         {
             T& data = stack1.top();
             stack1.pop();
             stack2.push(data);
         }
     }

     if(stack2.size() == ){
         std::logic_error ex("queue is empty");
         throw std::exception(ex);
     }

     T head = stack2.top();
     stack2.pop();

     return head;
 }

Queue.h