Submission #1020192

#	Time	Username	Problem	Language	Result	Execution time	Memory
1020192		mansur	Combo (IOI18_combo)	C++17	30 / 100	27 ms	1968 KiB

combo

#include "combo.h"
#include<bits/stdc++.h>

using namespace std;

#define rall(s) s.rbegin(), s.rend()
#define all(s) s.begin(), s.end()
#define sz(s) (int)s.size()
#define s second
#define f first

using ll = long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;

mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());

const int N = 1e6;

string guess_sequence(int n) {
	string ans = "";
	if (press("AB")) {
		if (press("A")) ans = "A";
		else ans = "B";
	}else {
		if (press("X")) ans = "X";
		else ans = "Y";
	}
	vector<char> s, h;
	if (ans != "A") s.push_back('A');
	if (ans != "B") s.push_back('B');
	if (ans != "X") s.push_back('X');
	if (ans != "Y") s.push_back('Y');
	while (sz(ans) < n) {
		shuffle(all(s), rng);
		if (sz(h)) {
			if (sz(ans) == n - 1) {
				if (press(ans + h[0]) == sz(ans)) ans += h[1];
				else ans += h[0];
				return ans;
			}
			int x = press(ans + h[0] + s[0] + ans + h[0] + s[1]);
			if (x == sz(ans) + 2) {
				ans += h[0];
				h = {s[0], s[1]};
				continue;
			}
			if (x == sz(ans) + 1) {
				ans = ans + h[0] + s[2];
				h.clear();
				continue;
			}
			ans += h[1];
			h.clear();
			continue;
		}
		if (sz(ans) == n - 1) {
			if (press(ans + s[0] + ans + s[1]) == sz(ans) + 1) {
				if (press(ans + s[0]) == sz(ans) + 1) ans += s[0];
				else ans += s[1];
			}else ans += s[2];
			return ans;
		}
		int x = press(ans + s[0] + s[0] + ans + s[0] + s[1] + ans + s[1] + s[0] + ans + s[1] + s[1]);
		if (x == sz(ans)) {
			ans += s[2];
			continue;
		}
		if (x == sz(ans) + 1) {
			if (press(ans + s[0]) == sz(ans)) ans = ans + s[1] + s[2];
			else ans = ans + s[0] + s[2];
			continue;
		}
		x = press(ans + s[0] + s[0]);
		if (x == sz(ans)) {
			ans += s[1];
			h = {s[0], s[1]};
			continue;
		}
		if (x == sz(ans) + 2) ans = ans + s[0] + s[0];
		else ans = ans + s[0] + s[1];
	}
	return ans;
}

• Subtask 1: 5 / 5
• Subtask 2: 25 / 95