#pragma GCC optimize("O1,O2,O3,Ofast,unroll-loops")
#include <bits/stdc++.h>
using namespace std;
#define fi first
#define se second
#define pb push_back
typedef long long ll;
typedef pair<int, int> ii;
typedef vector<int> vi;
#include "combo.h"
map<char, int> conv = {{'A', 0}, {'B', 1}, {'X', 2}, {'Y', 3}};
char convr[4] = {'A', 'B', 'X', 'Y'};
char firstLetter() { // finds first letter
int res = press("AB");
if (res >= 1) {
int res2 = press("A");
if (res2 == 1)
return 'A';
else
return 'B';
}
else {
int res2 = press("X");
if (res2 == 1)
return 'X';
else
return 'Y';
}
}
char nextLetter(string s) { // finds next letter
// cout<<"at "<<s<<endl;
int K = s.size();
char fs = s[0]; // first character
vector<char> opt; // posssible next letters
for (int i = 0; i < 4; i++) {
if (convr[i] != fs)
opt.pb(convr[i]);
}
vector<string> nx;
// ends with opt[0]
for (int i = 0; i < 3; i++) {
nx.pb(s + opt[0] + opt[i]);
}
// ends with opt[1]
nx.pb(s + opt[1]);
// ends with opt[2]
/* cout<<"nx: ";
for (string st : nx)
cout<<st<<" ";
cout<<endl;*/
string tq; // to query
for (int i = 0; i < 4; i++) {
tq += nx[i];
}
int res = press(tq);
// cout<<"res: "<<res<<endl;
if (res == K + 2)
return opt[0];
else if (res == K + 1)
return opt[1];
return opt[2];
}
char lastLetter(string s) {
int K = s.size();
char fs = s[0]; // first character
vector<char> opt; // posssible next letters
for (int i = 0; i < 4; i++) {
if (convr[i] != fs)
opt.pb(convr[i]);
}
int r1 = press(s + opt[0]);
int r2 = press(s + opt[1]);
if (r1 == K + 1)
return opt[0];
if (r2 == K + 1)
return opt[1];
return opt[2];
}
string guess_sequence(int N) {
string s;
char c = firstLetter();
s += c;
for (int i = 1; i < N - 1; i++) { // guess ith letter
char cp = nextLetter(s);
s += cp;
}
char cn = lastLetter(s);
s += cn;
// cout<<"found "<<s<<endl;
return s;
}
