Submission #803177

#	Time	Username	Problem	Language	Result	Execution time	Memory
803177		ALeonidou	Combo (IOI18_combo)	C++17	97 / 100	27 ms	624 KiB

combo

#include "combo.h"
using namespace std;

#define ll long long
string guess_sequence(int n) {
    string p, s = "";
    string w = "ABXY";

    //find first letter (3 operations)
    ll a = press("A"), b = press("B"), x = press("X");
    ll f = 3;
    if (a) f = 0;
    else if (b) f = 1;
    else if (x) f = 2;
    s += w[f];
    w.erase(w.begin() + f);

    if (n == 1) return s;

    //find all letters until n-1 (n-2 operations)
    for (ll i =1; i<n-1; i++){
        p = s + w[0] + s + w[1] + w[0] + s + w[1] + w[1] + s + w[1] + w[2];
        //dbg2(s,p);
        x = press(p);
        if (x == i) s += w[2];
        else if (x == i+1) s += w[0];
        else s += w[1];
    }

    //find last letter (2 operations)
    a = press(s + w[0]), b = press(s + w[1]);
    if (a == b) s += w[2];
    else if (a > b) s += w[0];
    else s += w[1]; 

    //dbg(s);

    return s;    
}

• Subtask 1: 5 / 5
• Subtask 2: 92 / 95