Submission #306147

#	Time	Username	Problem	Language	Result	Execution time	Memory
306147		lolicon	Counting Mushrooms (IOI20_mushrooms)	C++14	53.55 / 100	11 ms	584 KiB

mushrooms

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

int count_mushrooms(int n) {
	int cnt = 0;
	if(n <= 200) {
		int ret = 1;
		vector<int> m(2);
		for(int i = 1; i < n; i++) {
			m[1] = i;
			if(use_machine(m) == 0) ret++; 
		}
		return ret;	
	}
	int k = sqrt(n);
	vector<int> arr(n, 0);
	for(int i = 1; i < 2 * k; i++) {
		vector<int> m;
		m.push_back(0);
		m.push_back(i);
		if(use_machine(m)) {
			arr[i] = 1; cnt++;
		}
	} 
	int ret = 2 * k - cnt;
	if(cnt >= k) { // 1 is more
		vector<int> keep;
		for(int i = 0; i < 2 * k; i++) {
			if(arr[i] == 1) keep.push_back(i);
		}
		int block = (int)keep.size() - 1;
		assert(block > 0);
		for(int i = 2 * k; i < n; i += block) {
			vector<int> ask;
			ask.push_back(keep[0]);
			for(int j = 0, k = 1; j + i < n && j < block; j++) {
				ask.push_back(j + i);
				ask.push_back(keep[k]); k++;
			}
			ret += use_machine(ask) / 2;
		}
	}
	else { // 0 is more
		vector<int> keep;
		for(int i = 0; i < 2 * k; i++) {
			if(arr[i] == 0) keep.push_back(i);
		}
		int block = (int)keep.size() - 1;
		assert(block > 0);
		for(int i = 2 * k; i < n; i += block) {
			vector<int> ask;
			ask.push_back(keep[0]);
			for(int j = 0, k = 1; j + i < n && j < block; j++) {
				ask.push_back(j + i);
				ask.push_back(keep[k]); k++;
			}
			ret += ((int)ask.size() / 2) - use_machine(ask) / 2;
		}
	}
	// [0, 2 * k)
	return ret;
}

• Subtask 1: 53.5545 / 100