Submission #481766

#	Time	Username	Problem	Language	Result	Execution time	Memory
481766		blue	Counting Mushrooms (IOI20_mushrooms)	C++17	56.64 / 100	11 ms	308 KiB

mushrooms

#include "mushrooms.h"
#include <vector>
#include <iostream>
using namespace std;
 
const int X = 199; //199
 
int ceil_div(int a, int b)
{
    return a/b + bool(a%b);
}
 
int count_mushrooms(int n)
{
    if(n <= 100)
    {
      int ans = 1;
      for(int i = 1; i < n; i++) ans += !use_machine(vector<int>{0, i});
      return ans;
    }
  
    vector<int> typ[2];
    typ[0].push_back(0);
    for(int i = 1; i <= min(n-1, X); i++)
        typ[ use_machine(vector<int>{0, i}) ].push_back(i);
 
    vector<int> ans{(int)typ[0].size(), (int)typ[1].size()};
 
    int base = (int)typ[0].size() > (int)typ[1].size() ? 0 : 1;
    int ct = (int)typ[base].size();
 
    // cerr << ans[0] << ' ' << ans[1] << '\n';
 
    for(int v = X+1; v < n; v += ct-1)
    {
        // cerr << "V = " << v << '\n';
        vector<int> query{typ[base][0]};
        for(int i = v; i < v+ct-1 && i < n; i++)
        {
            query.push_back(i);
            query.push_back(typ[base][i-v+1]);
        }
 
        int Q = use_machine(query);
        int rem = (int)query.size() - 1  -  Q;
 
        ans[base] += rem/2;
        ans[!base] += Q/2;
    }
    return ans[0];
}

• Subtask 1: 56.6416 / 100