Submission #528129

#	Time	Username	Problem	Language	Result	Execution time	Memory
528129		happypotato	Combo (IOI18_combo)	C++17	100 / 100	38 ms	684 KiB

combo

#include "combo.h"
#include <bits/stdc++.h>
using namespace std;
string guess_sequence(int N) {
    const string valid = "ABXY";
    char fir;
    string ans = "";
    if (press("AB")) {
        if (press("AX")) fir = 'A';
        else fir = 'B';
    } else {
        if (press("AX")) fir = 'X';
        else fir = 'Y';
    }
    ans += fir;
    if (N == 1) return ans;
    for (int i = 1; i < N - 1; i++) {
        string req = "";
        int cnt = 0;
        for (int j = 0; j < 4; j++) {
            if (valid[j] == fir) continue;
            cnt++;
            if (cnt == 1) continue;
            else if (cnt == 2) {
                req += ans + valid[j];
            } else {
                for (int k = 0; k < 4; k++) {
                    if (valid[k] == fir) continue;
                    req += ans + valid[j] + valid[k];
                }
            }
        }
        int res = press(req) - i;
        for (int j = 0; j < 4; j++) {
            if (valid[j] == fir) continue;
            if (res == 0) {
                ans += valid[j];
                break;
            }
            res--;
        }
    }
    int cnt = 0;
    for (int i = 0; i < 4; i++) {
        if (valid[i] == fir) continue;
        string tar = ans + valid[i];
        if (cnt == 2) return tar;
        if (press(tar) == N) return tar;
        cnt++;
    }
    return "";
}

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