Submission #1052356

#	Time	Username	Problem	Language	Result	Execution time	Memory
1052356		aykhn	Counting Mushrooms (IOI20_mushrooms)	C++17	56.78 / 100	6 ms	600 KiB

mushrooms

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

using namespace std;

int B = 137;

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

int count_mushrooms(int n) 
{
	for (int i = 1; i <= 200; i++)
	{
		if (2 * i + (n + i - 1) / i <= 2 * B + (n + B - 1) / B) B = i;
	}
	vector<int> v[2];
	vector<int> o(n);
	iota(o.begin(), o.end(), 0);
	shuffle(o.begin() + 1, o.end(), rng);
	v[0] = {0};
	int i = 1;
	for (; i < n && max(v[0].size(), v[1].size()) < B + 1; i += 2) 
	{
		if (i + 1 < n)
		{
			int x = use_machine({0, o[i], o[i + 1]});
			if (x == 0) v[0].push_back(o[i]), v[0].push_back(o[i + 1]);
			else if (x == 2) v[1].push_back(o[i]), v[0].push_back(o[i + 1]);
			else 
			{
				v[1].push_back(o[i + 1]);
				if (!use_machine({0, o[i]})) v[0].push_back(o[i]);
				else v[1].push_back(o[i]);
			}
		}
		else v[use_machine({0, o[i]})].push_back(o[i]);
	}
	int res = 0;
	for (int j = i; j < n; j += B)
	{
		vector<int> q;
		int sz = min(n, j + B) - j;
		for (int k = j; k < min(n, j + B); k++)
		{
			if (v[0].size() > v[1].size())
			{
				q.push_back(v[0][k - j]);
				q.push_back(o[k]);
			}
			else
			{
				q.push_back(v[1][k - j]);
				q.push_back(o[k]);
			}
		}
		if (v[0].size() > v[1].size())
		{
			q.push_back(v[0].back());
			res += sz - (use_machine(q) / 2);
		}
		else
		{
			q.push_back(v[1].back());
			res += use_machine(q) / 2;
		}
	}
	return res + v[0].size();

}

Compilation message (stderr)

mushrooms.cpp: In function 'int count_mushrooms(int)':
mushrooms.cpp:22:48: warning: comparison of integer expressions of different signedness: 'const long unsigned int' and 'int' [-Wsign-compare]
   22 |  for (; i < n && max(v[0].size(), v[1].size()) < B + 1; i += 2)
      |                  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~

• Subtask 1: 56.7839 / 100