Submission #125681

#	Time	Username	Problem	Language	Result	Execution time	Memory
125681		dragoon	Combo (IOI18_combo)	C++14	100 / 100	64 ms	1960 KiB

combo

#include "combo.h"
#include<string>
#include <assert.h>
#include <iostream>
#include <algorithm>
using namespace std;

string FindFirstChar() {
	if (press("AB")) {
		if (press("A")) return "A";
		else return "B";
	}
	if (press("X")) return "X";
	return "Y";
}

string guess_sequence(int N) {
	string now = FindFirstChar();
	if (N == 1) return now;
	string remaining = "ABXY";
	remaining.erase(find(remaining.begin(), remaining.end(), now[0]));
	assert(remaining.size() == 3);
	for (int i = 2; i < N; i++) {
		string current = (now + remaining[0])
			+ (now + remaining[1] + remaining[0])
			+ (now + remaining[1] + remaining[1])
			+ (now + remaining[1] + remaining[2]);
		int coin = press(current);
		if (coin == i - 1) now.push_back(remaining[2]);
		else if (coin == i) now.push_back(remaining[0]);
		else now.push_back(remaining[1]);
	}

	for (int i = 0; i < 2; i++) {
		if (press(now + remaining[i]) == N) return now + remaining[i];
	}
	return now + remaining[2];
}

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