Submission #579978

#	Time	Username	Problem	Language	Result	Execution time	Memory
579978		Sharky	Combo (IOI18_combo)	C++17	100 / 100	43 ms	580 KiB

combo

#include "combo.h"
#include <bits/stdc++.h>
using namespace std;
std::string guess_sequence(int n) {
    string ans = "", c = "ABXYABXY";
    int res, pos;
    if (press("AB")) {
        if (press("A")) ans += 'A';
        else ans += 'B';
    } else {
        if (press("X")) ans += 'X';
        else ans += 'Y';
    }
    char f = ans[0];
    if (f == 'A') pos = 4;
    if (f == 'B') pos = 1;
    if (f == 'X') pos = 2;
    if (f == 'Y') pos = 3; 
    if (n == 1) return ans; 
    for (int i = 1; i < n - 1; i++) {
        string q = ans + c[pos + 1] + ans + c[pos + 2] + c[pos + 1] + ans + c[pos + 2] + c[pos + 2] + ans + c[pos + 2] + c[pos + 3];
        res = press(q);
        int len = ans.length();
        if (res == len + 1) ans += c[pos + 1];
        else if (res == len + 2) ans += c[pos + 2];
        else ans += c[pos + 3];
    }
    if (press(ans + c[pos + 2] + ans + c[pos + 1]) == n) {
        if (press(ans + c[pos + 2]) == n) ans += c[pos + 2];
        else ans += c[pos + 1];
    } else {
        ans += c[pos + 3];
    }
    return ans; 
}

#ifndef EVAL

namespace {

constexpr int MAX_N = 2000;
constexpr int MAX_NUM_MOVES = 8000;

int N;
std::string S;

int num_moves;

void wrong_answer(const char *MSG) {
  printf("Wrong Answer: %s\n", MSG);
  exit(0);
}

}  // namespace

int press(std::string p) {
    cout << p << "\n";
  if (++num_moves > MAX_NUM_MOVES) {
    wrong_answer("too many moves");
  }
  int len = p.length();
  if (len > 4 * N) {
    wrong_answer("invalid press");
  }
  for (int i = 0; i < len; ++i) {
    if (p[i] != 'A' && p[i] != 'B' && p[i] != 'X' && p[i] != 'Y') {
      wrong_answer("invalid press");
    }
  }
  int coins = 0;
  for (int i = 0, j = 0; i < len; ++i) {
    if (j < N && S[j] == p[i]) {
      ++j;
    } else if (S[0] == p[i]) {
      j = 1;
    } else {
      j = 0;
    }
    coins = std::max(coins, j);
  }
  return coins;
}

int main() {
  char buffer[MAX_N + 1];
  if (scanf("%s", buffer) != 1) {
    fprintf(stderr, "Error while reading input\n");
    exit(1);
  }
  S = buffer;
  N = S.length();

  num_moves = 0;
  std::string answer = guess_sequence(N);
  if (answer != S) {
    wrong_answer("wrong guess");
    exit(0);
  }
  printf("Accepted: %d\n", num_moves);
  return 0;
}

#endif

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