Submission #1033232

#	Time	Username	Problem	Language	Result	Execution time	Memory
1033232		vjudge1	Colors (BOI20_colors)	C++17	100 / 100	1 ms	600 KiB

Colors

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

#define int long long
#define ll long long
#define ar array
#define ld long double

const int N = 3e5 + 20;
const int B = 400;
const int M = 200;
const int INF = 1e15;
const int LOG = 24;
const int MOD = 998244353;

#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx,bmi,bmi2,lzcnt,popcnt")

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

signed main(){ios_base::sync_with_stdio(false);cin.tie(0);
	int n;
	cin>>n;
	int l = 0;
	int r = n;
	vector<int> v;
	while(l + 1 < r)v.push_back((l + r) / 2), l = (l + r) / 2;

	int pos = 1;
	reverse(v.begin(), v.end());
	for(auto u: v){
		if(pos + u <= n)pos += u;
		else pos -= u;
	}
	map<int,bool> vis;
	vis[pos] = 1;
	l = 0, r = n;
	query(pos);
	while(l +1 < r){
		int mid = (l + r)/ 2;
		if(pos + mid <= n && !vis[pos + mid]){
			pos += mid;
		}else pos -= mid;
		vis[pos] = 1;
		if(query(pos))r = mid;
		else l = mid;
	}
	cout<<"= "<<r<<endl;
}

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