Submission #172048

#	Time	Username	Problem	Language	Result	Execution time	Memory
172048		nobik	Combo (IOI18_combo)	C++14	100 / 100	72 ms	680 KiB

combo

#include "combo.h"
#include <bits/stdc++.h>

using namespace std;

string guess_sequence(int n) {
  string chars[] = {"A", "B", "X", "Y"};
  int first = 0;
  if (press("AB") > 0) {
    first = press("B");
  } else {
    first = 2 + press("Y");
  }

  string r = chars[first];
  if (n == 1)
    return r;

  vector<int> ids;
  for (int j = 0; j < 4; ++j) {
    if (j == first) continue;
    ids.push_back(j);
  }
  
  for (int i = 0; i < n - 2; ++i) {
    string f = r + chars[ids[0]];
    string s = r + chars[ids[1]];
    string query = (f + chars[ids[0]]) + (f + chars[ids[1]]) + (f + chars[ids[2]]) + s;
    int c = press(query);
    if (c == (int) f.size() + 1) r += chars[ids[0]]; else 
    if (c == (int) s.size()) r += chars[ids[1]]; else
    r += chars[ids[2]];
  }

  if (press(r + chars[ids[0]]) == n) r += chars[ids[0]]; else 
  if (press(r + chars[ids[1]]) == n) r += chars[ids[1]]; else
  r += chars[ids[2]];
  
  return r;
}


/*
Usage:
 std::string p = "";
  for (int i = 0; i < 4 * N; ++i) {
    p += 'A';
  }
  int coins = press(p);
  std::string S = "";
  for (int i = 0; i < N; ++i) {
    S += 'A';
  }
  return S;
*/

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