题解 | #【模板】栈#基于面向对象思想

#include <iostream>
#include <vector>

using namespace std;


class MyStack {

    vector<int> arr;

public:
    void push(int x) {
        arr.push_back(x);
    }

    void pop() {
        if (arr.empty()) {
            cout << "error" << endl;
            return;
        }
        cout<<arr.at(arr.size() - 1)<<endl;
        arr.pop_back();
    }

    void top() {
        if (arr.empty()) {
            cout << "error" << endl;
            return;
        }
        int num = arr.at(arr.size() - 1);
        cout << num << endl;
    }


};

int main() {
    int n;
    cin >> n;

    MyStack stack;

    for (int i = 0; i < n; i++) {
        string op;
        int num;
        while (cin >> op) {
            if (op == "push") {
                cin >> num;
                stack.push(num);
            } else if (op == "pop") {
                stack.pop();
            } else if (op == "top") {
                stack.top();
            }
        }
    }
    return 0;
}

// 64 位输出请用 printf("%lld")