两个栈共享同一存储空间

#include <iostream>
using namespace std;

const int StackSize = 100;

class BothStack
{

private:
    int data[StackSize];  ///存放两个栈的数组
    int top1, top2; ///两个栈的栈顶指针，分别为各自栈顶元素在数组中的下标

public:
    BothStack() {
        top1 = -1;
        top2 = StackSize;
    }  ///构造函数，将两个栈分别初始化
    ~BothStack() {} ///析构函数为空
    void Push(int i, int x); //入栈操作，将元素x压入栈i
    int Pop(int i);  ///出栈操作，对栈i执行出栈操作）
    int Empty(int i) {
        if (top1 == -1 && top2 == StackSize)
            return 1;
        else
            return 0;
    }  ///判断栈是否为空

};

void BothStack::Push(int i, int x) ///入栈操作，将元素x入栈
{
    if (top1 == top2 - 1)  throw "上溢"; ///判断是否栈满
    if (i == 1)  data[++top1] = x; ///在栈1中插入
    if (i == 2)  data[--top2] = x; ///在栈2中插入
}

int BothStack::Pop(int i)  ///出栈操作，将栈顶元素弹出
{
    if (i == 1) { ///在栈1中删除
        if (top1 == -1) ///判断栈1是否为空
            throw "下溢";
        return data[top1--];
    }
    if (i == 2) { ///在栈2中删除
        if (top2 == StackSize) ///判断栈2是否为空
            throw "下溢";
        return data[top2++];
    }
}

int main()
{
	BothStack B;
	B.Push(1,1);
	B.Push(2,2);
	B.Push(1,3);
	B.Push(2,4);
	cout << B.Pop(1) <<endl;
	cout << B.Pop(1) <<endl;
	cout << B.Empty(1) <<endl;
    return 0;
}