Submission #679936

#	Time	Username	Problem	Language	Result	Execution time	Memory
679936		Cyanmond	Zagrade (COI20_zagrade)	C++17	100 / 100	847 ms	952 KiB

zagrade

#include <bits/stdc++.h>

bool query(int l, int r) {
    std::cout << '?' << ' ' << l + 1 << ' ' << r << std::endl;
    int res;
    std::cin >> res;
    return res == 1;
}

void answer(std::string s) {
    std::cout << '!' << ' ' << s << std::endl;
    std::exit(0);
}

int main() {
    int N, Q;
    std::cin >> N >> Q;

    std::stack<int> stk;
    std::string ans(N, '0');
    int l = 0;
    for (int i = 1; i < N; ++i) {
        const int r = i + 1;
        const auto res = query(l, r);
        if (res) {
            ans[l] = '(';
            ans[i] = ')';
            if (stk.empty()) {
                l = i + 1;
                ++i;
            } else {
                l = stk.top();
                stk.pop();
            }
        } else {
            stk.push(l);
            l = i;
        }
    }

    const int count_zero = std::count(ans.begin(), ans.end(), '0');
    int c = 0;
    for (int i = 0; i < N; ++i) {
        if (ans[i] == '0') {
            ans[i] = c < count_zero / 2 ? ')' : '(';
            ++c;
        }
    }
    answer(ans);
}

• Subtask 1: 14 / 14
• Subtask 2: 7 / 7
• Subtask 3: 57 / 57
• Subtask 4: 22 / 22