Вводный курс: основы C++ | Урок 4: Меняем размер вектора 1/2

#include <iostream>
#include <string>
#include <vector>

using namespace std;

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

    vector<bool>queue;

    for (int i = 0; i < q; ++i) {
        string operation_code;
        cin >> operation_code;

        if (operation_code == "WORRY"s) {
            int index;
            cin >> index;
            queue[index] = true;
        }

        else if (operation_code == "HAPPY"s) {
            int index;
            cin >> index;
            queue[index] = false;
        }

        else if (operation_code == "COME"s) {
            int count;
            cin >> count;
            queue.resize(queue.size()+count, false);
        }

        else if (operation_code == "LAST_WORRY"s) {
            if (!queue.empty()) {
                if (queue.back() == true) {
                    cout << "worry" << endl;
                }
                else if (queue.back() == false) {
                    cout << "happy" << endl;
                }
            }
        }
    }
}