简单易懂

一条条照题面抄就行

#include<bits/stdc++.h>
using namespace std;
int a[114514];//题目纯吓人，根本不会这么大
int top;
int main() {
	int m;
	int n;
	string s;
	cin >> m;
	while (m--) {
		cin >> s;
		if (s == "push") {
			cin >> n;
			a[++top] = n;
		} else if (s == "pop") {
			if (top > 0) {
				cout << "pop " << a[top] << endl;
				top--;
			} else cout << "pop fail" << endl;
		} else if (s == "top") {
			if (top > 0)cout << "top = " << a[top] << endl;
			else cout << "top fail" << endl;
		} else if (s == "size")cout << "size = " << top << endl;
		else {
			if (top == 0)cout << "yes" << endl;
			else cout << "no" << endl;
		}
	}
	return 0;
}