Submission #235717

#	Time	Username	Problem	Language	Result	Execution time	Memory
235717		Hehehe	Combo (IOI18_combo)	C++14	100 / 100	41 ms	600 KiB

combo

#include "combo.h"

std::string guess_sequence(int N) {
    std::string t = "";
    char first, a[5];

    //first letter

    int p = press("AB"), k = 0, sz = 0;

    if(p == 2){
        t += "AB"; first = 'A'; sz = 2;
    }else
    if(p == 1){
        int x = press("A");
        if(x)t += "A";else t += "B";
        sz = 1; first = t[0];
    }else{
        int x = press("X");
        if(x)t += "X";else t += "Y";
        sz = 1; first = t[0];
    }

    if (first != 'A') a[k++] = 'A';
    if (first != 'B') a[k++] = 'B';
    if (first != 'X') a[k++] = 'X';
    if (first != 'Y') a[k++] = 'Y';


    //middle

    while (sz <= N - 2){
        std::string temp = t + a[0] + a[0];
        temp += t + a[0] + a[1];
        temp += t + a[0] + a[2];
        temp += t + a[1];
        p = press(temp);
        if (p - sz == 0) t += a[2];
        else if (p - sz == 1) t += a[1];
        else t += a[0];
        sz++;
    }

    //end

    //check end
    if (sz == N - 1){
        p = press(t + "A" + t + "B");
        if (p == N){
            p = press(t + "A");
            if (p == N) t += "A";
            else t += "B";
        }else{
            p = press(t + "X");
            if (p == N) t += "X";
            else t += "Y";
        }
    }

    return t;
}

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