Submission #75676

#	Time	Username	Problem	Language	Result	Execution time	Memory
75676		idLe	Combo (IOI18_combo)	C++14	100 / 100	53 ms	492 KiB

combo

#include "combo.h"

std::string guess_sequence(int N) {
    std::string t = "";
    char first, tr[5];
    //check first
    int p = press("AB"), sz = 0, k = 0;
    if (!p){
        p = press("X");
        if (p == 1) t += "X", first = 'X';
        else t += "Y", first = 'Y';
        sz++;
    }
    else if (p == 1){
        p = press("A");
        if (p == 1) t += "A", first = 'A';
        else t += "B", first = 'B';
        sz++;
    }
    else t += "AB", sz += 2, first = 'A';
    if (first != 'A') tr[k++] = 'A';
    if (first != 'B') tr[k++] = 'B';
    if (first != 'X') tr[k++] = 'X';
    if (first != 'Y') tr[k++] = 'Y';
    //check middle
    while (sz <= N - 2){
        std::string temp = t + tr[0] + tr[0];
        temp += t + tr[0] + tr[1];
        temp += t + tr[0] +  tr[2];
        temp += t + tr[1];
        p = press(temp);
        if (p - sz == 0) t += tr[2];
        else if (p - sz == 1) t += tr[1];
        else t += tr[0];
        sz++;
    }
    //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