Submission #361471

#	Time	Username	Problem	Language	Result	Execution time	Memory
361471		phathnv	Colors (BOI20_colors)	C++11	100 / 100	90 ms	512 KiB

Colors

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;

int Ask(ll x){
    cout << "? " << x << endl;
    int res;
    cin >> res;
    return res;
}

int main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);

    ll n;
    cin >> n;
    ll l = 1, r = n - 1, start = 1, cur = -1, dir = -1;
    while (l <= r){
        ll mid = (l + r) >> 1;
        cur += mid * dir;
        dir *= -1;
        l = mid + 1;
        start = max(start, -cur);
    }

    l = 1, r = n - 1, cur = start, dir = -1;
    Ask(start);
    ll answer = n;
    while (l <= r){
        ll mid = (l + r) >> 1;
        cur += mid * dir;
        dir *= -1;
        if (Ask(cur)){
            answer = mid;
            r = mid - 1;
        } else {
            l = mid + 1;
        }
    }

    cout << "= " << answer << endl;

    return 0;
}

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