Submission #331620

#	Time	Username	Problem	Language	Result	Execution time	Memory
331620		Falcon	Combo (IOI18_combo)	C++17	100 / 100	45 ms	748 KiB

combo

#include "combo.h"
#include <iostream>
#include <cassert>

std::string guess_sequence(int N) {
  std::string p = "";

  if(press("AB"))
      p = press("A") ? "A" : "B";
  else
      p = press("X") ? "X" : "Y";

  if(N == 1) return p;

  std::string chars = "";
  for(const char c : std::string("ABXY"))
      if(c && c != p[0])
          chars += c;

  assert(int(chars.size()) == 3);

  for(int i = 1; i < N - 1; ++i) { 
      assert(int(p.size()) == i);
      std::string a, b, c, d;
      a = p + chars[0];
      b = p + chars[1] + chars[0];    
      c = p + chars[1] + chars[1];
      d = p + chars[1] + chars[2];
      switch(press(a + b + c + d) - i) {
          case 0:
              p += chars[2];
              break;
          case 1:
              p += chars[0];
              break;
          case 2:
              p += chars[1];
              break;
          default:
              std::cout << p << ' ' << press(a + b + c + d) << ' ' << i << '\n';
              assert(0);
      }
  }

  assert(int(p.size()) == N - 1);

  for(const char c : chars)
      if(c != chars[0] && press(p + c) == N) {
          p += c;
          break;
      }

  if(int(p.size()) == N - 1) p += chars[0];
  
  assert(int(p.size()) == N);

  return p;
}

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