Submission #404340

#	Time	Username	Problem	Language	Result	Execution time	Memory
404340		hltk	Combo (IOI18_combo)	C++17	100 / 100	55 ms	568 KiB

combo

#include "combo.h"
#include <bits/stdc++.h>
using namespace std;
string guess_sequence(int N) {
  string p;
  if (press("AB")) {
    p = press("A") ? "A" : "B";
  } else {
    p = press("X") ? "X" : "Y";
  }
  if (N == 1) return p;
  vector<char> opts{'A', 'B', 'X', 'Y'};
  opts.erase(find(opts.begin(), opts.end(), p[0]));
  for (int i = 1; i < N - 1; ++i) {
    string k;
    k += p + opts[0] + opts[0];
    k += p + opts[0] + opts[1];
    k += p + opts[0] + opts[2];
    k += p + opts[1];
    int c = press(k);
    if (c == i + 2) {
      p += opts[0];
    } else if (c == i + 1) {
      p += opts[1];
    } else {
      p += opts[2];
    }
  }
  for (int j = 0; j < 2; ++j) {
    if (press(p + opts[j]) == N) {
      return p + opts[j];
    }
  }
  return p + opts[2];
}

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