#include "combo.h"
#include <bits/stdc++.h>
#define ll long long
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define watch(x) cout << (#x) << " : " << x << '\n'
#define boost ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
using namespace std;
//const string hidden = "XYYYYYYY";
//
//int press(string s) {
// cout << "ask " << s << '\n';
// int res = 0, pt = 0;
// for (int i = 0; i < (int)s.size(); i++) {
// if (hidden[pt] == s[i])
// pt++;
// else
// pt = 0;
// res = max(res, pt);
// if (pt == (int)hidden.size())
// break;
// }
// return res;
//}
string make_string(char x) {
string res;
res += x;
return res;
}
string guess_sequence(int N) {
// guess first letter
int n = N;
const vector<char> symb = {'A', 'B', 'X', 'Y'};
vector <int> order(4);
iota(all(order), 0);
random_shuffle(all(order));
char blocked = '.';
for (int i = 0; i < 4; i++) {
if (i == 3) {
blocked = symb[order[i]];
} else {
int c = press(make_string(symb[order[i]]));
if (c == 0)
continue;
blocked = symb[order[i]];
break;
}
}
assert(blocked != '.');
int pos = -1;
for (int i = 0; i < 4; i++)
if (symb[order[i]] == blocked)
pos = i;
assert(pos != -1);
order.erase(order.begin() + pos);
assert((int)order.size() == 3);
vector <char> ss;
for (auto i : order)
ss.push_back(symb[i]);
string pref = make_string(blocked);
if (n == 1)
return pref;
for (int i = 1; i + 1 < n; i++) {
vector <string> parts;
parts.push_back(pref+ss[0]);
parts.push_back(pref+ss[1]+ss[0]);
parts.push_back(pref+ss[1]+ss[1]);
parts.push_back(pref+ss[1]+ss[2]);
string tot = "";
for (auto& c : parts)
tot += c;
assert((int)tot.size() <= 4 * n);
int c = press(tot);
if (c == i)
pref += ss[2];
else if (c == i + 1)
pref += ss[0];
else if (c == i + 2)
pref += ss[1];
}
assert((int)pref.size() == n - 1);
for (auto& x : ss) {
int c = press(pref+x);
if (c != n)
continue;
pref += x;
break;
}
return pref;
}
//main() {
// srand(time(NULL));
// boost;
//
// string res = guess_sequence((int)(hidden.size()));
//
// cout << "res = " << res << '\n';
// cout << (res == hidden ? "correct" : "incorrect") << '\n';
//
// return 0;
//}
