陣列描述棧

#pragma warning(disable:4996)
#include <iostream>
#include<iterator>
#include<algorithm>
using namespace std;

//邊長一維陣列（增加或減少）
//改變一個一維陣列的長度
template<class T>
void changeLength1D(T*& a, int oldLength, int newLength)
{
	if (newLength < 0)
	{
		cout << "錯誤：newLength 小於 0！";
		exit(-1);
	}
	T* temp = new T[newLength];
	int number = min(oldLength, newLength);
	copy(a, a + number, temp);
	delete[] a;
	a = temp;
}

template<class T>
class stack
{
public:
	virtual ~stack() {};
	virtual bool empty() const = 0;
	virtual int size() const = 0;
	virtual T& top() = 0;
	virtual void pop() = 0;
	virtual void push(const T& theElement) = 0;
};

template<class T>
class arrayStack :public stack<T>
{
public:
	arrayStack(int initialCapacity = 10);
	~arrayStack() { delete[] stack; }
	bool empty() const { return stackTop == -1; }
	int size() const { return stackTop + 1; }
	T& top()
	{
		if (stackTop == -1)
		{
			cout << "棧中沒有元素" << endl;
			exit(-1);
		}
		return stack[stackTop];
	}
	void pop()
	{
		if (stackTop == -1)
		{
			cout << "棧中沒有元素" << endl;
			exit(-1);
		}
		stack[stackTop--].~T();
	}
	void push(const T& theElement);
	void output(ostream& out) const;
private:
	friend ostream& operator<<(ostream& out, const arrayStack<T>& x);
	//當前棧頂
	int stackTop;
	//棧容量
	int arrayLength;
	//元素陣列
	T *stack;
};
template<class T>
arrayStack<T>::arrayStack(int initialCapacity)
{
	if (initialCapacity < 1)
	{
		cout << "initialCapacity must be > 0" << endl;
		exit(-1);
	}
	arrayLength = initialCapacity;
	stack = new T[arrayLength];
	stackTop = -1;
}

template<class T>
void arrayStack<T>::push(const T& theElement)
{
	//判斷是否還有空間
	if (stackTop == arrayLength - 1)
	{
		changeLength1D(stack, arrayLength, 2 * arrayLength);
		arrayLength *= 2;
	}
	stack[++stackTop] = theElement;
}

template<typename T> ostream& operator<<(ostream& out, const arrayStack<T>& x)
{
	x.output(out);
	return out;
}

template<typename T> void arrayStack<T>::output(ostream& out) const
{
	//把棧插入輸出流
	copy(stack, stack + stackTop + 1, ostream_iterator<T>(cout, " "));
}

int main()
{
	arrayStack<int> s;
	s.push(1);
	s.push(2);
	s.push(3);
	s.push(4); 
	cout << "初始棧為：";
	s.output(cout);
	cout << endl;
	cout << "棧頂元素" <<s.top() << endl;
	s.pop();
	s.output(cout);
	cout << endl;
	cout << "棧存放的元素數量"<<s.size() << endl;
	
	system("pause");
	return 0;
}
 

連結串列描述棧

當用連結串列描述棧時，必須要確定用連結串列的哪段作為棧頂。若用連結串列的右端作為棧頂，則棧操作top、push和pop的實現需要用時O(size())。而用連結串列的左端作為棧頂，需要呼叫的連結串列方法是get(0)、insert(0,theElement)和erase(0)，其中每一個連結串列方法需要用時O(1)。所以選擇連結串列的左端作為棧頂。

#pragma warning(disable:4996)
#include <iostream>
using namespace std;

//連結串列節點的結構定義
template<class T>
struct chainNode
{
	T element;
	chainNode<T> *next;

	chainNode() {}
	chainNode(const T& element)
	{
		this->element = element;
	}
	chainNode(const T& element, chainNode<T>* next)
	{
		this->element = element;
		this->next = next;
	}
};

template<class T>
class stack
{
public:
	virtual ~stack() {};
	virtual bool empty() const = 0;
	virtual int size() const = 0;
	virtual T& top() = 0;
	virtual void pop() = 0;
	virtual void push(const T& theElement) = 0;
};

template<class T>
class linkStack :public stack<T>
{
public:
	linkStack()
	{
		stackTop = NULL;
		stackSize = 0;
	}
	~linkStack();
	bool empty() const
	{
		return stackSize == 0;
	}
	int size() const
	{
		return stackSize;
	}
	T& top()
	{
		if (stackSize == 0)
		{
			cout << "棧內無元素" << endl;
			exit(-1);
		}
		return stackTop->element;
	}
	void pop();
	void push(const T& theElement);
	void output(ostream& out) const;
private:
	friend ostream& operator<<(ostream& out, const linkStack<T>& x);
	//棧頂指標
	chainNode<T>* stackTop;
	//棧中元素個數
	int stackSize;
};

template<class T>
void linkStack<T>::pop()
{
	if (stackSize == 0)
	{
		cout << "棧內無元素" << endl;
		exit(-1);
	}
	chainNode<T>* nextNode = stackTop->next;
	delete stackTop;
	stackTop = nextNode;
	stackSize--;
}

template<class T>
void linkStack<T>::push(const T& theElement)
{
	stackTop = new chainNode<T>(theElement, stackTop);
	stackSize++;
}

template<class T>
linkStack<T>::~linkStack()
{
	while (stackTop != NULL)
	{
		chainNode<T>* nextNode = stackTop->next;
		delete stackTop;
		stackTop = nextNode;
	}
}

template<typename T> ostream& operator<<(ostream& out, const linkStack<T>& x)
{
	x.output(out);
	return out;
}

template<class T>
void linkStack<T>::output(ostream& out) const
{
	for (chainNode<T>* nextNode = stackTop; nextNode != NULL;
	nextNode = nextNode->next)
		out << nextNode->element << " ";
}

int main()
{
linkStack<int> s;
s.push(1);
s.push(2);
s.push(3);
s.push(4);
cout << "初始棧為：";
s.output(cout);
cout << endl;
cout << "棧頂元素" <<s.top() << endl;
s.pop();
s.output(cout);
cout << endl;
cout << "棧存放的元素數量"<<s.size() << endl;

system("pause");
return 0;
}
 

用陣列棧解決括號匹配問題

int main()
{
	arrayStack<int> s;
	string expr;
	getline(cin, expr);
	int length = (int)expr.size();
	for (int i = 0; i < length; ++i)
	{
		if (expr[i] == '(')
			s.push(i);
		else if (expr[i] == ')')
		{
			if (s.empty())
				cout << "沒有和右括號"<<i<<"匹配的左括號" << endl;
			else
			{
				cout << s.top() << ' ' << i << endl;
				s.pop();
			}
		}
	}
	while (!s.empty())
	{
		cout << "沒有和左括號"<<s.top()<<"匹配的右括號" << endl;
		s.pop();
	}
	system("pause");
	return 0;
}