STL了解一下
C++ 代码
#include <iostream>
#include <cstdio>
#include <stack>
using namespace std;
stack < int > s;
int n;
string a;
int main()
{
scanf("%d", &n);
while(n --)
{
cin >> a;
if(a == "push")
{
int x;
scanf("%d", &x);
s.push(x);
}
else if(a == "pop") s.pop();
else if(a == "empty")
if(s.empty()) printf("YES\n");
else printf("NO\n");
else if(a == "query") printf("%d\n", s.top());
}
return 0;
}