Submission #805155

#	Time	Username	Problem	Language	Result	Execution time	Memory
805155		rnl42	Colors (BOI20_colors)	C++14	100 / 100	2 ms	336 KiB

Colors

#include <bits/stdc++.h>
using namespace std;
#define int long long

int N;

inline int getvalid(int N) {
    int mincur = 0;
    int cur = 0;
    int mini = 1, maxi = N;
    bool parity = false;
    while (mini < maxi) {
        int mid = (mini+maxi-1)>>1;
        if (!parity) {
            cur += mid;
        } else {
            cur -= mid;
        }
        mini = mid+1;
        parity ^= 1;
        mincur = min(mincur, cur);
    }
    return -mincur;
}

inline bool query(int x) {
    cout << "? " << x+1 << '\n' << flush;
    bool ret;
    cin >> ret;
    return ret;
}

signed main() {
    //ios::sync_with_stdio(false), cin.tie(0), cout.tie(0);
    cin >> N;
    int cur = getvalid(N);
    int mini = 1, maxi = N;
    query(cur);
    bool parity = false;
    while (mini < maxi) {
        int mid = (mini+maxi-1)>>1;
        if (!parity) {
            cur += mid;
        } else {
            cur -= mid;
        }
        if (query(cur)) {
            maxi = mid;
        } else {
            mini = mid+1;
        }
        parity ^= 1;
    }
    cout << "= " << mini << '\n';
}

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