剑指offer八：用两个栈实现队列

 

 

#include<iostream>
#include<stack>

using namespace std;

//定义模板类，参数T可以是任意的类型，后面实例化的时候指出即可
template <typename T> class Queue
{
public:
	Queue(void) {};
	~Queue(void) {};
	void appendTail(const T& node);
	T deleteHead();
private:
	stack<T> stack1;
	stack<T> stack2;
};

//模板类里得函数的定义
template <typename T> void Queue<T>::appendTail(const T& element)
{
	stack1.push(element);
}

template<typename T> T Queue<T>::deleteHead()
{
	if (stack2.size() == 0)//stack.size()求的是栈里的元素个数
	{
		while (stack1.size() > 0)
		{
			T& data = stack1.top();
			stack1.pop();
			stack2.push(data);
		}
	}
	T head = stack2.top();
	stack2.pop();
	return head;
}

int main()
{
	Queue<char> queue1;//模板类的实例化对象
	char *s = "abc";
	queue1.appendTail(s[0]);
	queue1.appendTail(s[1]);
	queue1.appendTail(s[2]);
	
	char result = queue1.deleteHead();
	cout << result << endl;
}

 

相关题目：用两个队列实现栈

 

#include<iostream>
#include<queue>
using namespace std;

template<typename T> class Stack
{
public:
	Stack() {};
	~Stack(){};
	void appendHead(const T& data);
	T deleteHead();
private:
	queue<T>queue1;
	queue<T>queue2;
	queue<T>temp;
};

template<typename T> void Stack<T>::appendHead(const T& data)
{
	queue1.push(data);
}

template<typename T> T Stack<T>::deleteHead()
{
	while (queue1.size() > 1)
	{
		T& data = queue1.front();
		queue1.pop();
		queue2.push(data);
	}
	T head = queue1.front();
	queue1.pop();
	temp = queue1;
	queue1 = queue2;
	queue2 = temp;
	return head;
}

int main()
{
	Stack<char> stack1;
	char* s = "abcde";
	char result;
	stack1.appendHead(s[0]);
	stack1.appendHead(s[1]);
	stack1.appendHead(s[2]);
	stack1.appendHead(s[3]);

	result = stack1.deleteHead();
	cout << result << endl;

	result = stack1.deleteHead();
	cout << result << endl;
}