Submission #709808

#	Time	Username	Problem	Language	Result	Execution time	Memory
709808		Cyanmond	Combo (IOI18_combo)	C++17	100 / 100	37 ms	580 KiB

combo

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

std::string guess_sequence(int N) {
    char firstC;
    if (press("AB") >= 1) {
        if (press("A") == 1) {
            firstC = 'A';
        } else {
            firstC = 'B';
        }
    } else {
        if (press("X") == 1) {
            firstC = 'X';
        } else {
            firstC = 'Y';
        }
    }
    if (N == 1) {
        std::string res = "";
        res += firstC;
        return res;
    }
    std::vector<char> cs = {'A', 'B', 'X', 'Y'};
    for (int i = 0; i < 4; ++i) {
        if (cs[i] == firstC) {
            cs.erase(cs.begin() + i);
            break;
        }
    }

    std::string answer = "";
    answer += firstC;
    for (int i = 1; i < N - 1; ++i) {
        std::string x = answer;
        x += cs[1];
        x += answer;
        x += cs[0];
        x += cs[0];
        x += answer;
        x += cs[0];
        x += cs[1];
        x += answer;
        x += cs[0];
        x += cs[2];
        const auto res = press(x);
        if (res == i) {
            answer += cs[2];
        } else if (res == i + 1) {
            answer += cs[1];
        } else {
            answer += cs[0];
        }
    }
    if (press(answer + 'A' + answer + 'B') == N) {
        if (press(answer + 'A') == N) {
            answer += 'A';
        } else {
            answer += 'B';
        }
    } else {
        if (press(answer + 'X') == N) {
            answer += 'X';
        } else {
            answer += 'Y';
        }
    }
    return answer;
}

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