Submission #1128561

#	Time	Username	Problem	Language	Result	Execution time	Memory
1128561		mbalsells	Combo (IOI18_combo)	C++20	0 / 100	0 ms	396 KiB

combo

#include "combo.h"

using namespace std;
// ABXY

string buttons = "ABXY";

int get_index(string& s){
  for (int i = 0; i < 4; ++i){
    if (s[0] == buttons[i]) return i;
  }
}

char get_first(){
  if (press("AB") == 1){
    if (press("A")) return 'A';
    else return 'B';
  }
  else {
    if (press("X") == 1) return 'X';
    else return 'Y';
  }
}

char get_next(string s){
  int index = get_index(s);
  string left_buttons;
  for (int i = 1; i <= 3; ++i){
    left_buttons.push_back(buttons[(index + i) % 4]);
  }

  int l = s.size();
  string query = s;
  query.push_back(left_buttons[0]);

  for (int i = 0; i < 3; ++i){
    query += s;
    query.push_back(left_buttons[1]);
    query.push_back(left_buttons[i]);
  }

  int response = press(query);
  if (response == l) return left_buttons[2];
  if (response == l + 1) return left_buttons[0];
  return left_buttons[1];
}

char get_last(string& s){
  int index = get_index(s);
  string left_buttons;
  for (int i = 1; i <= 3; ++i){
    left_buttons.push_back(buttons[(index + i) % 4]);
  }

  int l = s.size();
  string query = s;
  query.push_back(left_buttons[0]);

  if (press(query) == l + 1) return left_buttons[0];

  query = s;
  query.push_back(left_buttons[1]);

  if (press(query) == l + 1) return left_buttons[1];
  return left_buttons[2];
}

std::string guess_sequence(int N) {
  string ans;
  ans.push_back(get_first());

  if (N == 1) return ans;

  for (int i = 2; i < N; ++i){
    ans.push_back(get_next(ans));
  }

  ans.push_back(get_last(ans));  
  return ans;
}

Compilation message (stderr)

combo.cpp: In function 'int get_index(std::string&)':
combo.cpp:12:1: warning: control reaches end of non-void function [-Wreturn-type]
   12 | }
      | ^

• Subtask 1: 0 / 5
• Subtask 2: 0 / 95