백준 10828 스택

b10828.cpp

#include <iostream>
#include <vector>

using namespace std;

class stack {
private:
    int a[10000];
    int i = -1;
public:
    void push(int x);
    int pop();
    int size();
    int empty();
    int top();
};

void stack::push(int x) { a[++i] = x; }

int stack::pop() {
    if (empty()) return -1;
    else return a[i--];
}

int stack::size() { return (empty()) ? 0 : i + 1; }

int stack::empty() { return (i == -1) ? 1 : 0; }

int stack::top() { 
    if (empty()) return -1;
    else return a[i];
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    
    stack stk;
    int n;
    cin >> n;
    while (n--) {
        string s;
        cin >> s;
        if (s == "push") {
            int t;
            cin >> t;
            stk.push(t);
        }
        else if (s == "pop") cout << stk.pop() << '\n';
        else if (s == "size") cout << stk.size() << '\n';
        else if (s == "empty") cout << stk.empty() << '\n';
        else if (s == "top") cout << stk.top() << '\n';
    }
    
    return 0;
}