Submission #830815

#	Time	Username	Problem	Language	Result	Execution time	Memory
830815		amunduzbaev	Counting Mushrooms (IOI20_mushrooms)	C++17	75.84 / 100	7 ms	444 KiB

mushrooms

#include "mushrooms.h"

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

#define ar array
typedef long long ll;
//~ #define int ll

const int N = 20'000;

int count_mushrooms(int n){
	vector<int> p[2];
	p[0].push_back(0);
	
	int B = 50;
	//~ for(int i=1;i<=N;i++){
		//~ if(2 * i + (N + i - 1) / i < 2 * B + (N + B - 1) / B){
			//~ B = i;
		//~ }
	//~ }
	
	int last = 1;
	for(int i=1;i<n && max((int)p[0].size(), (int)p[1].size()) < B;i++){
		last++;
		if(use_machine({0, i})) p[1].push_back(i);
		else p[0].push_back(i);
	}
	
	ar<int, 2> cc {};
	cc[0] = p[0].size(), cc[1] = p[1].size();
	
	for(int i=last;i<n;){
		int B = p[0].size(); 
		bool is = 1;
		if((int)p[1].size() > B) is = 0, B = p[1].size();
		
		int j = min(i + B, n);
		
		vector<int> qq;
		for(int k=i;k<j;k++){
			qq.push_back(p[is ^ 1][k - i]);
			qq.push_back(k);
		}
		
		int c = use_machine(qq);
		if(c & 1) cc[is]++, p[is].push_back(j - 1), c--;
		else cc[is ^ 1]++, p[is ^ 1].push_back(j - 1);
		
		cc[is] += c / 2, cc[is ^ 1] += (j - i - 1 - c / 2);
		i = j;
	}
	
	return cc[0];
}

• Subtask 1: 75.8389 / 100