Submission #1035902

#	Time	Username	Problem	Language	Result	Execution time	Memory
1035902		Mr_Husanboy	Counting Mushrooms (IOI20_mushrooms)	C++17	88.28 / 100	6 ms	712 KiB

mushrooms

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

using namespace std;

#define ll long long
#define all(a) (a).begin(), (a).end()
#define ff first
#define ss second

template<typename T>
int len(T &a){return a.size();}

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


int count_mushrooms(int n) {
	if(n < 226){
		int ans = 1;
		for(int i = 1; i < n; i ++){
			ans += use_machine({0, i}) ^ 1;
		}
		return ans;
	}

	vector<int> a = {0}, b;

	int i = 1;
	while(len(a) < 2 && len(b) < 2){
		if(use_machine({0, i})){
			b.push_back(i);
		}else{
			a.push_back(i);
		}
		i ++;
	}
	int sq = sqrtl(n) / 2;
	while(len(a) < sq && len(b) < sq){
		if(len(a) >= 2){
			int cnt = use_machine({a[0], i, a[1], i + 1});
			if(cnt == 0){
				a.push_back(i);
				a.push_back(i + 1);
			}
			if(cnt == 1){
				a.push_back(i);
				b.push_back(i + 1);
			}
			if(cnt == 2){
				b.push_back(i);
				a.push_back(i + 1);
			}
			if(cnt == 3){
				b.push_back(i);
				b.push_back(i + 1);
			}
			i += 2;
		}else{
			int cnt = use_machine({b[0], i, b[1], i + 1});
			if(cnt == 3){
				a.push_back(i);
				a.push_back(i + 1);
			}
			if(cnt == 2){
				a.push_back(i);
				b.push_back(i + 1);
			}
			if(cnt == 1){
				b.push_back(i);
				a.push_back(i + 1);
			}
			if(cnt == 0){
				b.push_back(i);
				b.push_back(i + 1);
			}
			i += 2;
		}
	}
	if(len(a) >= len(b)){
		ll ans = len(a);
		while(i < n){
		vector<int> req;
			for(int j = 0; j < len(a) && i < n; j ++){
				req.push_back(a[j]);
				req.push_back(i);
				i ++;
			}
			int cnt = use_machine(req);
			ans += len(req) / 2 - (cnt + 1) / 2;
			if(cnt & 1){
				b.push_back(req.back());
			}else a.push_back(req.back());
		}
		return ans;
	}else{
		ll ans = len(a);
		while(i < n){
		vector<int> req;
			for(int j = 0; j < len(b) && i < n; j ++){
				req.push_back(b[j]);
				req.push_back(i);
				i ++;
			}

			int cnt = use_machine(req);
			ans += (cnt + 1) / 2;
			if(cnt & 1){
				a.push_back(req.back());
			}else b.push_back(req.back());
		}
		return ans;
	}
}

• Subtask 1: 88.2812 / 100