Submission #112751

#	Time	Username	Problem	Language	Result	Execution time	Memory
112751		fredbr	Combo (IOI18_combo)	C++17	100 / 100	57 ms	552 KiB

combo

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

using namespace std;

string first_guess() {
    static string t1("AB");
    int ans = press(t1);

    if (ans) {
        if (press("A"))
            return "A";
        else
            return "B";
    }
    else {
        if (press("X"))
            return "X";
        else return "Y";
    }
}


string guess_sequence(int n) {
    string ans = first_guess();
    if (n == 1) return ans;
  
    string f = ans;

    vector<string> poss;

    for (string a : {"A", "B", "X", "Y"}) {
        if (a != f) poss.push_back(a);
    }

    vector<string> comb = {poss[0]+poss[0],
                           poss[0]+poss[1],
                           poss[0]+poss[2],
                           poss[1]};

    for (int i = 1; i < n-1; i++) {
        string tmpans = ans + comb[0] + ans + comb[1] + ans + comb[2] + ans + comb[3];

        int x = press(tmpans);

        switch (x-i) {
            case 2:
                ans += poss[0];
                break;
            case 1:
                ans += poss[1];
                break;
            case 0:
                ans += poss[2];
                break;
        }
    }

    ans += poss[0];
    if (press(ans) == n) {
        return ans;
    }
    ans.pop_back();
    
    ans += poss[1];
    if (press(ans) == n) {
        return ans;
    }

    ans.pop_back();
    ans += poss[2];
    return ans;
}

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