Submission #679264

#	Time	Username	Problem	Language	Result	Execution time	Memory
679264		That_Salamander	Combo (IOI18_combo)	C++14	30 / 100	50 ms	592 KiB

combo

#include <cstdio>
#include <cstdlib>
#include <algorithm>
#include <string>
#include <bits/stdc++.h>

using namespace std;

int press(std::string p);

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

std::string guess_sequence(int N) {
  //Get first char
  int first;
  if (press("AB")) {
    if (press("A")) {
        first = 0;
    } else {
        first = 1;
    }
  } else if (press("X")) {
    first = 2;
  } else {
    first = 3;
  }

  string res = " ";res[0] = CHARS[first];

  vector<char> cs;
  for (char c: CHARS) {
    if (c != CHARS[first]) cs.push_back(c);
  }

  for (int i = 0; i < N - 1; i++) {
    if (press(res + cs[0] + res + cs[1]) == res.size() + 1) {
        if (press(res + cs[0]) == res.size() + 1) {
            res += cs[0];
        } else {
            res += cs[1];
        }
    } else {
        res += cs[2];
    }
  }

  return res;
}




#ifdef LOCAL_TEST
#include <random>
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();*/

    for (int i = 0;  i< 1000; i++) {
        N = rand() % 50 + 1;

        S.resize(N);

        for (int i = 0; i < N; i++) {
            char c;
            do {
                c = CHARS[rand() % 4];
            } while (i != 0 && S[0] == c);
            S[i] = c;
        }

        cout << S << endl;

        num_moves = 0;
        std::string answer = guess_sequence(N);
        if (answer != S) {
            cout << "Guess:\n" << answer << endl;
            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:36:42: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   36 |     if (press(res + cs[0] + res + cs[1]) == res.size() + 1) {
      |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~
combo.cpp:37:32: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   37 |         if (press(res + cs[0]) == res.size() + 1) {
      |             ~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~

• Subtask 1: 5 / 5
• Subtask 2: 25 / 95