Submission #873991

#	Time	Username	Problem	Language	Result	Execution time	Memory
873991		kh0i	Combo (IOI18_combo)	C++17	100 / 100	15 ms	2016 KiB

combo

#include "combo.h"
#include "bits/stdc++.h"
using namespace std;

#define sz(x) (int)(x).size()

string guess_sequence(int N) {
    string p = "";
    string S = "";

    int a, b, x;
    a = b = x = 0;
    if(press("AB")){
        if(press("A"))
            a = 1;
        else b = 1;
    }
    else{
        if(press("X"))
            x = 1;
    }

    if(a) S = "A";
    else if(b) S = "B";
    else if(x) S = "X";
    else S = "Y";

    vector<string> choice;

    if(a) choice = {"B", "XX", "XB", "XY", "Y"};
    else if(b) choice = {"A", "XX", "XA", "XY", "Y"};
    else if(x) choice = {"A", "BB", "BA", "BY", "Y"};
    else choice = {"A", "BB", "BA", "BX", "X"};

    if(N == 1)
        return S;

    for(int i = 1; i < N - 1; ++i){
        string to_press = "";
        for(int j = 0; j < 4; ++j){
            // cerr << S << ' ' << choice[j] << endl;
            to_press += S + choice[j];
        }
        int len = press(to_press);
        if(len == sz(S))
            S += choice.back();
        else if(len == sz(S) + 1)
            S += choice.front().front();
        else
            S += choice[1].front();
    }

    if(press(S + choice[0]) == N)
        S += choice[0];
    else if(press(S + choice[1][0]) == N)
        S += choice[1][0];
    else
        S += choice.back();

    return S;
}

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