Submission #113171

#	Time	Username	Problem	Language	Result	Execution time	Memory
113171		IOrtroiii	Combo (IOI18_combo)	C++14	100 / 100	49 ms	536 KiB

combo

#include <bits/stdc++.h>
#include "combo.h"
using namespace std;

string cs = "ABXY";

string guess_sequence(int n) {
   int first = -1;
   string ans;
   if (press("AB")) {
      if (press("A")) ans = "A", first = 0;
      else ans = "B", first = 1;
   } else {
      if (press("X")) ans = "X", first = 2;
      else ans = "Y", first = 3;
   }
   if (n == 1) return ans;
   assert(first != -1);
   for (int i = 0; i < n - 2; ++i) {
      string q = "";
      int cnt = 0;
      for (int j = 0; j < 4; ++j) if (j != first) {
         if (cnt == 1) {
            q += ans + cs[j];
         } else if (cnt == 2) {
            for (int k = 0; k < 4; ++k) if (k != first) {
               q += ans + cs[j] + cs[k];
            }
         }
         ++cnt;
      }
      int cur = press(q);
      cnt = ans.size();
      for (int j = 0; j < 4; ++j) if (j != first) {
         if (cnt == cur) {
            ans += cs[j];
         }
         ++cnt;
      }
   }

   if (press(ans + "A" + ans + "B") == n) {
      if (press(ans + "A") == n) return ans + "A";
      else return ans + "B";
   } else {
      if (press(ans + "X") == n) return ans + "X";
      else return ans + "Y";
   }
}

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