使用数组来模拟栈操作

#include<bits/stdc++.h>
using namespace std;
const int N = 100010;
int n;
int stk[N],tt;
//栈顶插入元素
void mypush(int x)
{
    stk[tt++] = x;
}
//出栈操作
int mypop()
{
    int res = stk[tt];
    tt--;
    return res;
}
//栈空
bool myempty()
{
    if(stk[tt-1]){
        return false;
    }else{
        return true;
    }
}
//查询栈顶元素
int find()
{
    return stk[tt-1];
}


int main()
{
    cin >> n;
    while(n--)
    {
        string op;
        int x;
        cin >> op;
        if(op == "push"){
            cin >> x;
            mypush(x);
        }else if(op == "pop"){
            mypop();
        }else if(op == "query"){
            cout << find() << endl;
        }else{
            if(myempty()){
                cout << "YES" << endl;
            }else{
                cout << "NO" << endl;
            }
        }
    }
    return 0;
}