Submission #679263

#	Time	Username	Problem	Language	Result	Execution time	Memory
679263		That_Salamander	Combo (IOI18_combo)	C++14	10 / 100	81 ms	548 KiB

combo

#include <cstdio>
#include <cstdlib>
#include <algorithm>
#include <string>

int press(std::string p);

char CHARS[4] = {'A', 'B', 'X', 'Y'};

std::string guess_sequence(int N) {
  std::string p = "";
  while (p.size() < N) {
    for (int i = 0; i < 4; i++) {
        if (press(p + CHARS[i]) == p.size() + 1) {
            p += CHARS[i];
            break;
        }
    }
  }

  return p;
}




#ifdef LOCAL_TEST
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) {
  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

Compilation message (stderr)

combo.cpp: In function 'std::string guess_sequence(int)':
combo.cpp:12:19: warning: comparison of integer expressions of different signedness: 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   12 |   while (p.size() < N) {
      |          ~~~~~~~~~^~~
combo.cpp:14:33: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   14 |         if (press(p + CHARS[i]) == p.size() + 1) {
      |             ~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~

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