Submission #304813

#	Time	Username	Problem	Language	Result	Execution time	Memory
304813		sofapuden	Colors (BOI20_colors)	C++14	100 / 100	4 ms	512 KiB

Colors

#include <bits/stdc++.h>

using namespace std;
typedef long long ll;

ll fS(ll x){
	ll lo = 1, hi = x-1, cn = 0, ans = -1, out = 1;
	while(cn <= 80){
		if(cn&1)ans-=(lo+hi)/2;
		else ans +=(lo+hi)/2;
		lo = (lo+hi)/2+1;
		out = min(out, ans);
		cn++;
	}
	return out;
}
		
		

int main(){
	ll n; cin >> n;
	ll start = -fS(n);
	cout << "? " << start << endl;
	ll tr; cin >> tr;
	ll lo = 1LL, hi = n-1LL, cn = 0LL, best = n, ans = start, x;
	while(lo <= hi){
		ll mid =(lo+hi)/2LL;
		if(cn&1)ans-=mid;
		else ans+=mid;
		cout << "? " << ans << endl;
		cin >> x;
		if(x){
			hi = mid-1LL;
			best = mid;
		}
		else{
			lo = mid+1LL;
		}
		cn++;
	}
	cout << "= " << best << endl;
}

	
	

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