Submission #203867

#	Time	Username	Problem	Language	Result	Execution time	Memory
203867		dung11112003	Combo (IOI18_combo)	C++11	100 / 100	66 ms	580 KiB

combo

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

#define taskname ""
#define pb push_back
#define eb emplace_back
#define fi first
#define se second
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define for0(i, n) for (int i = 0; i < (int)(n); ++i)
#define for1(i, n) for (int i = 1; i <= (int)(n); ++i)
#define ford(i, n) for (int i = (int)(n) - 1; i >= 0; --i)
#define fore(i, a, b) for (int i = (int)(a); i <= (int)(b); ++i)

using namespace std;

typedef long long ll;
typedef long double ld;
typedef complex <ld> cd;
typedef vector <cd> vcd;
typedef vector <int> vi;

template<class T> using v2d = vector <vector <T> >;
template<class T> bool uin(T &a, T b)
{
    return a > b ? (a = b, true) : false;
}
template<class T> bool uax(T &a, T b)
{
    return a < b ? (a = b, true) : false;
}

mt19937 rng(chrono::system_clock::now().time_since_epoch().count());

const int maxN = 1e5 + 10;

int n;

string guess_sequence(int N)
{
    int n = N;
    string prefix = "";
    int p = press(prefix + "AB");
    char firstChar;
    if (p > 0)
    {
        p = press(prefix + "A");
        if (p > 0)
        {
            firstChar = 'A';
        }
        else
        {
            firstChar = 'B';
        }
    }
    else
    {
        p = press(prefix + "X");
        if (p > 0)
        {
            firstChar = 'X';
        }
        else
        {
            firstChar = 'Y';
        }
    }
    prefix += firstChar;
    if (n == 1)
    {
        return prefix;
    }
    vector <char> a;
    for (char c: {'A', 'B', 'X', 'Y'})
    {
        if (c != firstChar)
        {
            a.eb(c);
        }
    }
    fore(i, 2, n - 1)
    {
        p = press(prefix + a[0] + prefix + a[1] + a[0] + prefix + a[1] + a[1] + prefix + a[1] + a[2]);
        if (p == i - 1)
        {
            prefix += a[2];
        }
        else if (p == i)
        {
            prefix += a[0];
        }
        else
        {
            prefix += a[1];
        }
    }
    p = press(prefix + a[0]);
    if (p == n)
    {
        prefix += a[0];
    }
    else
    {
        p = press(prefix + a[1]);
        if (p == n)
        {
            prefix += a[1];
        }
        else
        {
            prefix += a[2];
        }
    }
    return prefix;
}

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