Submission #580026

#	Time	Username	Problem	Language	Result	Execution time	Memory
580026		Vanilla	Counting Mushrooms (IOI20_mushrooms)	C++17	80.14 / 100	11 ms	432 KiB

mushrooms

#include <bits/stdc++.h>
#include "mushrooms.h"
using namespace std;
int block = 141;

int cd2 (int x) {
	return x / 2 + (x % 2);
}

int count_mushrooms(int n) {
	if (n <= 20) {
		int rs = 0;
		for (int i = 1; i < n; i++){
			rs+=use_machine({0, i});
		}
		return n - rs;
	}
	block = min(n / 2, block);
	if (block * 2 == n) block--;
	vector <int> s0 = {0}, s1;
	int p1 = use_machine({0, 1});
	int p2 = use_machine({0, 2});
	(p1 ? s1: s0).push_back(1);
	(p2 ? s1: s0).push_back(2);
	if (p1 == p2 && p1 == 1) {
		for (int i = 3; i + 1 <= block * 2; i+=2){
			int k = use_machine({i, 1, i + 1, 2});
			(k & 1 ? s0: s1).push_back(i);
			(k & 2 ? s0: s1).push_back(i + 1);
		}
	}
	else {
		int p = (p1 == 0 ? 1: 2);
		for (int i = 3; i + 1 <= block * 2; i+=2){
			int k = use_machine({i, 0, i + 1, p});
			(k & 1 ? s1: s0).push_back(i);
			(k & 2 ? s1: s0).push_back(i + 1);
		}
	}
	bool rev = 0;
	int rs = s0.size();
	int oth = 0;
	if (s1.size() > s0.size()) {
		rev = 1;
		swap(s0, s1);
	}
	vector <int> idx;
	for (int i = block * 2 + 1; i < n; i++){
		idx.push_back(s0[i % block]);
		idx.push_back(i);
		if (i % block == 0 || i == n - 1) {
			oth+=cd2(use_machine(idx));
			idx.clear();
		}
	}
	if (!rev) oth = n - block * 2 - 1 - oth;
	return rs + oth;
}

• Subtask 1: 80.1418 / 100