Submission #299525

#	Time	Username	Problem	Language	Result	Execution time	Memory
299525		square1001	Combo (IOI18_combo)	C++14	100 / 100	40 ms	636 KiB

combo

#include "combo.h"
#include <string>
#include <iostream>
using namespace std;
std::string guess_sequence(int N) {
	// step #1. first letter
	int gi1 = press("AB"), gi2 = press("AX");
	char ci = '?';
	if(gi1 != 0 && gi2 != 0) ci = 'A';
	if(gi1 != 0 && gi2 == 0) ci = 'B';
	if(gi1 == 0 && gi2 != 0) ci = 'X';
	if(gi1 == 0 && gi2 == 0) ci = 'Y';
	// step #2. second to (N-1)-th letters
	string current(1, ci);
	for(int i = 1; i < N - 1; ++i) {
		char cn1 = '?', cn2 = '?', cn3 = '?';
		if(ci == 'A') cn1 = 'B', cn2 = 'X', cn3 = 'Y';
		if(ci == 'B') cn1 = 'X', cn2 = 'Y', cn3 = 'A';
		if(ci == 'X') cn1 = 'Y', cn2 = 'A', cn3 = 'B';
		if(ci == 'Y') cn1 = 'A', cn2 = 'B', cn3 = 'X';
		int g = press(current + cn1 + cn1 + current + cn1 + cn2 + current + cn1 + cn3 + current + cn2);
		if(g == i + 2) current += cn1;
		if(g == i + 1) current += cn2;
		if(g == i) current += cn3;
	};
	// step #3. N-th letter
	if(N >= 2) {
		int gl1 = press(current + "A" + current + "B");
		int gl2 = press(current + "A" + current + "X");
		if(gl1 == N && gl2 == N) current += "A";
		if(gl1 == N && gl2 != N) current += "B";
		if(gl1 != N && gl2 == N) current += "X";
		if(gl1 != N && gl2 != N) current += "Y";
	}
	return current;
}

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