Submission #139370

#	Time	Username	Problem	Language	Result	Execution time	Memory
139370		atoiz	Combo (IOI18_combo)	C++14	100 / 100	57 ms	2124 KiB

combo

#include "combo.h"
#include <vector>
#include <algorithm>
#include <cstdio>
#include <iostream>

using namespace std;

vector<char> ch = {'A', 'B', 'X', 'Y'};

char firstChar()
{
	int coins;

    coins = press(string(1, ch[0]) + string(1, ch[1]));
    if (coins == 2) return ch[0];
    else if (coins == 1) {
        coins = press(string(1, ch[0]));
        if (coins == 1) return ch[0];
        else {
            swap(ch[0], ch[1]);
            return ch[0];
        }
    } else {
        coins = press(string(1, ch[2]));
        if (coins == 1) {
            swap(ch[0], ch[2]);
            return ch[0];
        }
        else {
            swap(ch[0], ch[3]);
            return ch[0];
        }
    }
}

char lastChar(string S)
{
	int coins;
    coins = press(S + string(1, ch[0]) + S + string(1, ch[1]));
    if (coins == S.size() + 1) {
        coins = press(S + string(1, ch[0]));
        if (coins == S.size() + 1) return ch[0];
        else return ch[1];
    } else {
        coins = press(S + string(1, ch[2]));
        if (coins == S.size() + 1) return ch[2];
        else return ch[3];
    }
}

string guess_sequence(int N) {
    string S = string(1, firstChar());
    if (N == 1) return S;
	int coins;

	vector<string> str(4);
    for (int i = 0; i < 4; ++i) str[i] = string(1, ch[i]);

    for (int i = 2; i < N; ++i) {
//		cerr << S << ": " << S + str[1] + str[1] + S + str[1] + str[2] + S + str[1] + str[3] + S + str[2];
		coins = press(S + str[1] + str[1] + S + str[1] + str[2] + S + str[1] + str[3] + S + str[2]);
//        cerr << " " << coins << endl;
        if (coins == S.size() + 2) {
            S += str[1];
        } else if (coins == S.size() + 1) {
			S += str[2];
        } else {
			S += str[3];
        }
    }

    S += string(1, lastChar(S));
    return S;
}

Compilation message (stderr)

combo.cpp: In function 'char lastChar(std::string)':
combo.cpp:41:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   41 |     if (coins == S.size() + 1) {
      |         ~~~~~~^~~~~~~~~~~~~~~
combo.cpp:43:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   43 |         if (coins == S.size() + 1) return ch[0];
      |             ~~~~~~^~~~~~~~~~~~~~~
combo.cpp:47:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   47 |         if (coins == S.size() + 1) return ch[2];
      |             ~~~~~~^~~~~~~~~~~~~~~
combo.cpp: In function 'std::string guess_sequence(int)':
combo.cpp:64:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   64 |         if (coins == S.size() + 2) {
      |             ~~~~~~^~~~~~~~~~~~~~~
combo.cpp:66:26: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   66 |         } else if (coins == S.size() + 1) {
      |                    ~~~~~~^~~~~~~~~~~~~~~

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