剑指offer-->面试题7 用两个栈实现队列

#pragma once

#include <stack>
#include <exception>

using namespace std;

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

void appendTail(const T &node);
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& node)
{
stack1.push(node);
}

template <typename T> T CQueue<T>::deleteHead()
{
if(stack2.size() <= 0)
{
while(stack1.size() > 0)
{
T &data = stack1.top();
stack1.pop();
stack2.push(data);
}
}

if(stack2.size() == 0)
{
throw new exception("queue is empty");
}

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

return head;
}

#include <stdio.h>
#include "Queue.h"

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

int main()
{
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');

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

return 0;
}