Submission #971291

#	Time	Username	Problem	Language	Result	Execution time	Memory
971291		codefox	Combo (IOI18_combo)	C++14	97 / 100	25 ms	1908 KiB

combo

#include<bits/stdc++.h>
#include "combo.h"

using namespace std;

array<char, 4> arr = {'A', 'B', 'Y', 'X'};

char unknown(string s, int j, char f)
{
    string ss;
    string sol;
    for (int i = 0; i < j; i++)
    {
        ss+=s[i];
    }
    if (f=='A')
    {
        sol = ss+'B';
        sol += ss+"XX";
        sol += ss+"XB";
        sol += ss+"XY";
        int c = press(sol);
        if (c==j) return 'Y';
        if (c==j+1) return 'B';
        else return 'X';
    }
    if (f=='B')
    {
        sol = ss+'A';
        sol += ss+"XX";
        sol += ss+"XA";
        sol += ss+"XY";
        int c = press(sol);
        if (c==j) return 'Y';
        if (c==j+1) return 'A';
        else return 'X';
    }
    if (f=='Y')
    {
        sol = ss+'A';
        sol += ss+"BX";
        sol += ss+"BB";
        sol += ss+"BA";
        int c = press(sol);
        if (c==j) return 'X';
        if (c==j+1) return 'A';
        else return 'B';
    }
    if (f=='X')
    {
        sol = ss+'B';
        sol += ss+"AA";
        sol += ss+"AB";
        sol += ss+"AY";
        int c = press(sol);
        if (c==j) return 'Y';
        if (c==j+1) return 'B';
        else return 'A';
    }
}

string guess_sequence(int N) {
    char f = 'N';
    for (int i = 0; i < 3; i++)
    {
        string st = "";
        st += arr[i];
        if (press(st))
        {
            f = arr[i];
            break;
        }
    }
    if (f=='N') f = 'X';
    if (N==1) 
    {
        string s = "";
        s+=f;
        return s;
    }

    string s = "";
    s += f;
    for (int i = 1; i < N-1; i++)
    {
        s += unknown(s, i, f);
    }
    if (f!='A' && press(s+'A')==N) return s+'A';
    if (f!='B' && press(s+'B')==N) return s+'B';
    if (f =='X') return s+'Y';
    if (f=='Y') return s+'X';
    if (press(s+'Y')==N) return s+'Y';
    else return s+'X';
}

Compilation message (stderr)

combo.cpp: In function 'char unknown(std::string, int, char)':
combo.cpp:10:12: warning: control reaches end of non-void function [-Wreturn-type]
   10 |     string ss;
      |            ^~

• Subtask 1: 5 / 5
• Subtask 2: 92 / 95