题解 | #【模板】队列#

#include <iostream>
using namespace std;

int main() {
    int n = 0;
    cin >> n;
    int res[100000];
    int end = 0;
    int start = 0;

    for (int i = 0; i < n; i++) {
        string str;
        cin >> str;
        if (str == "push") {
            cin >> res[end++];
        } else if (str == "pop") {
            if (start < end) {
                cout << res[start++] << endl;
            } else {
                cout << "error" << endl;
            }
        } else if (str == "front") {
            if (start < end) {
                cout << res[start] << endl;
            } else {
                cout << "error" << endl;
            }
        }
    }
}