Submission #107248

#	Time	Username	Problem	Language	Result	Execution time	Memory
107248		wonyoung	Combo (IOI18_combo)	C++14	30 / 100	101 ms	716 KiB

combo

#include <vector>
#include <string>
using namespace std;
int press(string p);

string guess_sequence(int N)
{
    vector<char> buttons = { 'A', 'B', 'X', 'Y' };
    string prefix;
    char first_char;
    int n;
    n = press("AB");
    if (n == 2)
    {
        prefix = "AB";
        buttons.erase(buttons.begin());
    }
    else if (n == 1)
    {
        if (press("A") > 0)
        {
            prefix = "A";
            buttons.erase(buttons.begin());
        }
        else
        {
            prefix = "B";
            buttons.erase(buttons.begin()+1);
        }
    }
    else
    {
        if (press("X") > 0)
        {
            prefix = "X";
            buttons.erase(buttons.begin()+2);
        }
        else
        {
            prefix = "Y";
            buttons.erase(buttons.begin()+3);
        }
    }
    

    int i;
    bool skip = false;
    while (prefix.length() < N)
    {
        for (i=0; i< 2; i++)
        {
            if (i==0 && skip) {
                skip = false;
                continue;
            }
            string query_string = "";
            string s = prefix;
            s.push_back(buttons[i]);
            query_string += s;
            while (query_string.length() + s.length() + 1 < N * 4)
            {
                s.push_back(buttons[0]);
                query_string += s;
            }
            n = press(query_string);
            if (n > prefix.length())
            {
                if (n < s.length())
                {
                    skip = true;
                }
                break;
            }
        }
        prefix.push_back(buttons[i]);
        for (int i=prefix.length(); i<n; i++)
        {
            prefix.push_back(buttons[0]);
        }
    }

    return prefix;
}

Compilation message (stderr)

combo.cpp: In function 'std::string guess_sequence(int)':
combo.cpp:48:28: warning: comparison of integer expressions of different signedness: 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   48 |     while (prefix.length() < N)
      |            ~~~~~~~~~~~~~~~~^~~
combo.cpp:60:59: warning: comparison of integer expressions of different signedness: 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   60 |             while (query_string.length() + s.length() + 1 < N * 4)
      |                    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~
combo.cpp:66:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   66 |             if (n > prefix.length())
      |                 ~~^~~~~~~~~~~~~~~~~
combo.cpp:68:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   68 |                 if (n < s.length())
      |                     ~~^~~~~~~~~~~~
combo.cpp:10:10: warning: unused variable 'first_char' [-Wunused-variable]
   10 |     char first_char;
      |          ^~~~~~~~~~

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