Submission #230692

#	Time	Username	Problem	Language	Result	Execution time	Memory
230692		islingr	Combo (IOI18_combo)	C++14	100 / 100	60 ms	592 KiB

combo

#include <combo.h>
#include <iostream>
using namespace std;
#define rep(i, a, b) for (auto i = (a); i < (b); ++i)

char first = 'A';
string parse(string s) {
	for (char &c : s)
		if (c == 'A') c = first;
		else if (c == first) c = 'A';
	return s;
}
int ask(const string &p) { return press(parse(p)); }

string guess_sequence(int n) {
	if (ask("AB"))
		first = ask("A") ? 'A' : 'B';
	else
		first = ask("X") ? 'X' : 'Y';
	string cur{'A'};
	if (n > 1) {
		rep(i, 1, n - 1) {
			int cnt = ask(cur + "BB" + cur + "BX" + cur + "BY" + cur + "X");
			if (cnt == i + 0) cur += "Y";
			if (cnt == i + 1) cur += "X";
			if (cnt == i + 2) cur += "B";
		}
		if (ask(cur + "B" + cur + "X") == n)
			cur += ask(cur + "B") == n ? "B" : "X";
		else cur += "Y";
	}
	return parse(cur);
}

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