Submission #1223311

#	Time	Username	Problem	Language	Result	Execution time	Memory
1223311		hengliao	Colors (BOI20_colors)	C++20	100 / 100	1 ms	436 KiB

Colors

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

#define F first
#define S second
#define pll pair<ll, ll>
#define vll vector<ll>
#define pb push_back

typedef long long ll;

const ll inf=1e18;

ll qry(ll tar){
    cout<<"? "<<tar<<endl;
    ll re;
    cin>>re;
    return re;
}

void solve(){
    ll n;
    cin>>n;
    ll x=0;
    ll pos=1;   
    ll lef=1, rig=n-1;
    ll mx=0, mn=0;
    while(lef<=rig){
        ll mid=(lef+rig)/2;
        x+=pos*mid;
        mx=max(mx, x);
        mn=min(mn, x);
        pos*=-1;
        lef=mid+1;
    }   
    // cout<<mn<<' '<<mx<<endl;
    ll cur=1-mn;
    lef=1;
    rig=n-1;
    ll good=-1;
    qry(cur);
    pos=1;
    while(lef<=rig){
        ll mid=(lef+rig)/2;
        cur+=pos*mid;
        pos*=-1;
        if(qry(cur)){
            good=mid;
            rig=mid-1;
        }
        else{
            lef=mid+1;
        }
    }
    if(good==-1) cout<<"= "<<n<<endl;
    else cout<<"= "<<good<<endl;
}

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

  solve();

  return 0;
}

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