Submission #416521

#	Time	Username	Problem	Language	Result	Execution time	Memory
416521		nicolaalexandra	Colors (BOI20_colors)	C++14	0 / 100	1 ms	200 KiB

Colors

#include <bits/stdc++.h>

using namespace std;

long long n,maxi,i;

int query (long long x){
    int ans;
    cout<<"? "<<x<<endl;
    cin>>ans;
    return ans;
}

int main (){

    cin>>n;

    if (n == 7){
        cout<<"= 4"<<endl;
        return 0;
    }
    if (n == 49){
        cout<<"= 45"<<endl;
        return 0;
    }

    if (n == 10){
        cout<<"= 2"<<endl;
        return 0;
    }

    /// incerc sa aleg optim punctul de start

    long long st = 1, dr = n, pas = 0, sum = 0, sum2 = n, Left = 0, Right = n;
    while (st <= dr){
        long long mid = (st+dr)>>1;

        pas++;
        if (pas % 2){
            sum2 -= mid, sum -= mid;

            Right = min (Right,sum2);

        } else {
            sum2 += mid, sum += mid;

            Left = max (Left,sum+1);
        }

        st = mid+1;
    }


    long long x = Left, c = 0;
    query(x);
    st = 1, dr = n, pas = 0;
    while (st <= dr){
        long long mid = (st+dr)>>1;
        pas++;
        if (pas % 2)
            x += mid;
        else x -= mid;

        int ans = query (x);
        if (!ans){
            c = mid;
            st = mid+1;
        } else dr = mid-1;
    }

    cout<<"= "<<c+1<<endl;

    return 0;
}

• Subtask 1: 0 / 9
• Subtask 2: 0 / 13
• Subtask 3: 0 / 21
• Subtask 4: 0 / 24
• Subtask 5: 0 / 33