Submission #791721

#	Time	Username	Problem	Language	Result	Execution time	Memory
791721		pavement	Combo (IOI18_combo)	C++17	100 / 100	32 ms	676 KiB

combo

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

#define pb push_back

string guess_sequence(int N) {
	char st;
	int p = press("AB");
	if (p) {
		p = press("A");
		if (p) st = 'A';
		else st = 'B';
	} else {
		p = press("X");
		if (p) st = 'X';
		else st = 'Y';
	}
	vector<char> valid;
	for (char c : {'A', 'B', 'X', 'Y'}) {
		if (c != st) valid.pb(c);
	}
	string s = "";
	s.pb(st);
	if (N == 1) return s;
	for (int i = 1; i + 1 < N; i++) {
		string q = s;
		q.pb(valid[0]);
		q += s;
		q.pb(valid[1]);
		q.pb(valid[0]);
		q += s;
		q.pb(valid[1]);
		q.pb(valid[1]);
		q += s;
		q.pb(valid[1]);
		q.pb(valid[2]);
		int p = press(q);
		if (p == (int)s.size()) s.pb(valid[2]);
		else if (p == (int)s.size() + 1) s.pb(valid[0]);
		else s.pb(valid[1]);
	}
	p = press(s + valid[0] + s + valid[1]);
	if (p == (int)s.size() + 1) {
		p = press(s + valid[0]);
		if (p == (int)s.size() + 1) s += valid[0];
		else s += valid[1];
	} else {
		s += valid[2];
	}
	return s;
}

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