제출 #1131619

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
1131619		alterio	Colors (BOI20_colors)	C++20	100 / 100	1 ms	668 KiB

Colors

#include <bits/stdc++.h>

using namespace std;

#define endl '\n'
#define ll long long
#define all(x) (x).begin(), (x).end()

ll ask(ll x) {
    cout << "? " << x << endl;
    ll val;
    cin >> val;
    return val;
}

int main() {
    ll n;
    cin >> n;
    ll l = 0, r = n;
    ll pos = 1;
    vector<ll> v;
    while (l + 1 < r) {
        v.push_back((l + r) / 2);
        l = (l + r) / 2;
    }
    reverse(all(v));
    for (auto x : v) {
        if (pos + x <= n) pos += x;
        else pos -= x;
    }
    ask(pos);
    unordered_set<ll> used;
    used.insert(pos);
    l = 0, r = n;
    while (l + 1 < r) {
        ll mid = (l + r) / 2;
        if (pos + mid <= n && !used.count(pos + mid)) pos += mid;
        else pos -= mid;
        used.insert(pos);
        ll x = ask(pos);
        if (x) r = mid;
        else l = mid;
    }
    cout << "= " << r << endl;
}

• Subtask 1: 9 / 9
• Subtask 2: 13 / 13
• Subtask 3: 21 / 21
• Subtask 4: 24 / 24
• Subtask 5: 33 / 33