Submission #108127

#	Time	Username	Problem	Language	Result	Execution time	Memory
108127		autumn_eel	Combo (IOI18_combo)	C++14	100 / 100	51 ms	584 KiB

combo

#include <bits/stdc++.h>
#define rep(i,n)for(int i=0;i<(n);i++)
using namespace std;

#include "combo.h"

string s="ABXY";

string guess_sequence(int N) {
	function<char(string)>dfs=[&](string s){
		if(s.size()==1)return s[0];
		int res=press(s.substr(0,s.size()/2));
		if(res)return dfs(s.substr(0,s.size()/2));
		return dfs(s.substr(s.size()/2));
	};
	char c=dfs(s);
	string ans;ans+=c;
	if(N==1)return ans;
	string t;
	rep(i,4){
		if(s[i]!=c)t+=s[i];
	}
	for(int i=1;i<N-1;i++){
		string ask=ans+t[0];
		rep(j,3)ask+=ans+t[1]+t[j];
		int res=press(ask);
		if(res==i){
			ans+=t[2];
		}
		else if(res==i+1){
			ans+=t[0];
		}
		else if(res==i+2){
			ans+=t[1];
		}
		else abort();
	}
	char last='?';
	rep(i,2){
		int res=press(ans+t[i]);
		if(res==N){
			last=t[i];
			break;
		}
	}
	if(last=='?')last=t[2];
	ans+=last;
	return ans;
}

• Subtask 1: 5 / 5
• Subtask 2: 95 / 95