Submission #392910

#	Time	Username	Problem	Language	Result	Execution time	Memory
392910		wind_reaper	Colors (BOI20_colors)	C++17	100 / 100	6 ms	396 KiB

Colors

#include <bits/stdc++.h>

using namespace std;


int Ask(int64_t num){
	cout << "? " << num << endl;
	int x;
	cin >> x;
	return x; 
}

int32_t main(){
	ios_base::sync_with_stdio(false); 
	cin.tie(NULL); 
	
	int64_t n;
	cin >> n;

	int64_t l = 1, r = n-1, start = n, cur = 0, dir = 1;

	while(l <= r){
		int64_t mid = (l + r) / 2;
		cur += dir*mid;
		dir *= -1;
		start = min(start, n - cur);
		l = mid + 1;
	}

	l = 1, r = n-1, dir = 1;

	int64_t answer = n;	

	Ask(start);

	while(l <= r){
		int64_t mid = (l + r) / 2;
		int64_t ask = start + dir*mid;
		dir *= -1;
		if(Ask(ask)){
			answer = mid;
			r = mid - 1;
		}
		else l = mid + 1;
		start = ask;
	}
	
	cout << "= " << answer << '\n';	
	return 0; 
}

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