Submission #615379

#	Time	Username	Problem	Language	Result	Execution time	Memory
615379		AriaH	Combo (IOI18_combo)	C++17	97 / 100	50 ms	560 KiB

combo

#include "combo.h"
#pragma GCC optimize("O3")

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef long double ld;
typedef pair < int, int > pii;
typedef pair < ll, ll > pll;

#define F first
#define S second
#define all(x) x.begin(), x.end()
#define SZ(x) (int)x.size()
#define Mp make_pair
#define endl "\n"
#define fast_io ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);

const int N = 1e6 + 10;
const int LOG = 20;
const ll mod = 1e9 + 7;
const ll inf = 8e18;

string A[4] = {"A", "B", "X", "Y"};

vector < string > vec;

string guess_sequence(int n)
{
  mt19937 rng(time(nullptr));
  string ans;
  shuffle(A, A + 4, rng);
  for(int j = 0; j < 3; j ++)
  {
    if(press(A[j]))
    {
      ans += A[j];
      break;
    }
  }
  if(ans == "") ans += A[3];
  for(int j = 0; j < 4; j ++)
  {
    if(ans == A[j]) continue;
    vec.push_back(A[j]);
  }
  for(int i = 1; i < n - 1; i ++)
  {
    string now2 = ans + vec[2];
    string now = ans + vec[1] + now2 + vec[0] + now2 + vec[1] + now2 + vec[2];
    ans += vec[press(now) - i];
  }
  if(n - 1)
  {
    for(int j = 0; j < 2; j ++)
    {
      if(press(ans + vec[j]) == n)
      {
        ans += vec[j];
        break;
      }
    }
    if(SZ(ans) == n - 1) ans += vec[2];
  }
  return ans;
}

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