#include <string>
#include <vector>
#include <numeric>
#include <algorithm> // Required for std::find
// Forward declaration or include header
// #include "combo.h"
extern int press(std::string p);
std::string guess_sequence(int N) {
std::string guessed_S = "";
std::vector<char> all_chars = {'A', 'B', 'X', 'Y'};
char first_char = 0;
if (N == 0) {
return "";
}
// --- Step 1: Determine the first character S[0] ---
if (press("A") == 1) {
guessed_S = "A";
} else if (press("B") == 1) {
guessed_S = "B";
} else {
if (press("X") == 1) {
guessed_S = "X";
} else {
guessed_S = "Y";
}
}
first_char = guessed_S[0];
// --- Step 2: Determine the remaining characters S[1] to S[N-1] ---
while (guessed_S.length() < N) {
int k = guessed_S.length();
char next_char = 0;
// Identify candidates: c1, c2, c3 != first_char; c4 = first_char
std::vector<char> other_chars;
for (char c : all_chars) {
if (c != first_char) {
other_chars.push_back(c);
}
}
char c1 = other_chars[0];
char c2 = other_chars[1];
char c3 = other_chars[2];
char c4 = first_char; // Candidate 4 is the first char
// Query 1: Test pair (c1, c2)
int r1 = press(guessed_S + c1 + guessed_S + c2);
if (r1 == k + 1) {
// Case A: Possibilities are c1 or c2
// Query 2: Distinguish c1 / c2
int r2 = press(guessed_S + c1);
if (r2 == k + 1) {
next_char = c1;
} else { // r2 must be k
next_char = c2;
}
} else { // r1 == k
// Case B: Possibilities are c3 or c4
// Query 2: Distinguish c3 / c4
int r3 = press(guessed_S + c3);
if (r3 == k + 1) {
next_char = c3;
} else { // r3 must be k
next_char = c4; // The first character reappears
}
}
// Append the determined character
guessed_S.push_back(next_char);
}
return guessed_S;
}
