Submission #1052608

#	Time	Username	Problem	Language	Result	Execution time	Memory
1052608		TahirAliyev	Counting Mushrooms (IOI20_mushrooms)	C++17	92.62 / 100	6 ms	760 KiB

mushrooms

#include "mushrooms.h"
#include <bits/stdc++.h>
using namespace std;
#define pii pair<int, int>
#define ll long long
#define all(v) v.begin(), v.end()
#define oo 1e9
	
int count_mushrooms(int n){
	srand(time(0));
	//
	int B = 78;
	// pair<int, int> best = {oo, 0};
	// for(int x = 3; x <= n; x++) best = min(best, {2 + (2 * (x - 2)) / 2  + (x & 1) + (n - 1) / x, x});
	// B = best.second;
	//
	vector<int> id;		
	for(int i = 0; i < n; i++) id.push_back(i);
	random_shuffle(id.begin() + 1, id.end());
	vector<int> v[2];
	v[0] = {0};
	int i = 1;
	for(; i < min(3, n); i++){
		v[use_machine({0, id[i]})].push_back(i);
	}
	int t = (v[0].size() < v[1].size());
	for(; i + 1 < n && (int)max(v[0].size(), v[1].size()) < B; i += 2){
		int a = use_machine({id[i], id[v[t][0]], id[i + 1], id[v[t][1]]}); 
		v[t ^ (a & 1)].push_back(i);
		v[t ^ bool(a & 2)].push_back(i + 1);
	}
	if(i == n - 1){
		v[use_machine({0, id[i]})].push_back(i);
		i++;
	}
	int ans = v[0].size();
	if(i == n) return ans;
	while(i < n){
		t = (v[0].size() < v[1].size());
		vector<int> tmp;
		for(int j = 0; j < v[t].size() && i < n; j++, i++){
			tmp.push_back(id[v[t][j]]);
			tmp.push_back(id[i]);
		}
		int a = use_machine(tmp);
		if(a & 1) v[t ^ 1].push_back(i - 1);
		else v[t].push_back(i - 1);
		if(t) ans += (a + 1) / 2;
		else ans += (tmp.size() / 2) - (a + 1) / 2;
	}
	return ans;
}

Compilation message (stderr)

mushrooms.cpp: In function 'int count_mushrooms(int)':
mushrooms.cpp:41:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   41 |   for(int j = 0; j < v[t].size() && i < n; j++, i++){
      |                  ~~^~~~~~~~~~~~~

• Subtask 1: 92.623 / 100