Submission #763742

#	Time	Username	Problem	Language	Result	Execution time	Memory
763742		aaron_dcoder	Colors (BOI20_colors)	C++17	0 / 100	0 ms	208 KiB

Colors

#include <bits/stdc++.h>

using namespace std;
using ll = long long;

bool did_archie_notice(ll col) {
    int ans;
    cout << "? " << col << endl;
    cin >> ans;
    cout.flush();
    return (ans == 1);
}


int offset(ll N) {
    ll minimum_possible_value_C = 1ll;
    ll curren_hair_color = N/3ll;
    ll next_direc = 1ll;
    ll next_check;
    do {
        ll to_check = (N+minimum_possible_value_C)/2ll;
        ll oldhaircolor = curren_hair_color;
        next_check= curren_hair_color + next_direc*to_check;
        curren_hair_color = next_check;
        minimum_possible_value_C = abs(oldhaircolor-curren_hair_color)+1ll;
        next_direc *= -1ll;
        
    } while (next_check>1);
    return 1-next_check;
}


int main() {
    ll N;
    cin >> N;
    cout.flush();
    set<ll> used_up;
    ll curren_hair_color = N/3ll +offset(N);
    did_archie_notice(curren_hair_color);
    
    ll maximum_possible_value_C = N;
    ll minimum_possible_value_C = 1ll;

    ll next_direc = 1ll;

    while (maximum_possible_value_C!=minimum_possible_value_C) {
        //cout << "max pv:" << maximum_possible_value_C << ",min pv:" << minimum_possible_value_C << " ,haircol:" << curren_hair_color << "\n";
        ll to_check = (maximum_possible_value_C+minimum_possible_value_C)/2ll;
        ll oldhaircolor = curren_hair_color;
        bool hasnoticed = true;
        for (ll chk_disp = 0; ; chk_disp++) {
            ll next_check= curren_hair_color + next_direc*(to_check-chk_disp);
            if ((to_check-chk_disp) >= maximum_possible_value_C || (to_check-chk_disp) < minimum_possible_value_C) {
                throw exception();
            }
            if (used_up.count(next_check)==0) {
                used_up.insert(next_check);
                hasnoticed = did_archie_notice(next_check);
                curren_hair_color = next_check;
                break;
            }
            next_check= curren_hair_color + next_direc*(to_check+chk_disp);
            if ((to_check+chk_disp) >= maximum_possible_value_C || (to_check+chk_disp) < minimum_possible_value_C) {
                throw exception();
            }
            if (used_up.count(next_check)==0) {
                used_up.insert(next_check);
                hasnoticed = did_archie_notice(next_check);
                curren_hair_color = next_check;
                break;
            }
        }
        if (hasnoticed) {
            maximum_possible_value_C = abs(oldhaircolor-curren_hair_color);
        }
        else {
            minimum_possible_value_C = abs(oldhaircolor-curren_hair_color)+1ll;
        }
        next_direc *= -1ll;
    }

    cout << "= " << maximum_possible_value_C << endl;
}
    

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• Subtask 2: 0 / 13
• Subtask 3: 0 / 21
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