#include "combo.h"
#include <string>
#include <vector>
using namespace std;
#define BUT "ABXY"
string guess_sequence(int N)
{
string ans(2005, 0);
int j = 0;
vector<int> non(2005, 0);
for (int i = 0; i < 4; ++i)
{
ans.resize(2);
ans[0] = BUT[i];
ans[1] = 'A';
int k = press(ans);
ans[1] = 0;
if (k >= 1) ++j, non[1] |= 1;
if (k == 2) ++j, ans[1] = 'A';
if (k >= 1) break;
}
for (int i = j; i < N;)
{
int nxt = i + 1;
for (int j = 0; j < 4; j++)
{
if (non[i] & (1 << j)) continue;
ans.resize(i+2);
ans[i] = BUT[j];
ans[i+1] = i + 1 < N ? 'A' : 0;
int k = press(ans);
ans[i+1] = 0;
if (k == i + 2) { non[i+1] |= 1; nxt = i + 2; ans[i+1] = 'A'; }
if (k >= i + 1) goto FND;
}
FND:;
i = nxt;
}
ans.resize(N);
return ans;
}
