Submission #767555

#	Time	Username	Problem	Language	Result	Execution time	Memory
767555		adrilen	Counting Mushrooms (IOI20_mushrooms)	C++17	92.62 / 100	7 ms	452 KiB

mushrooms

	#include "mushrooms.h"
	#include<bits/stdc++.h>
	using namespace std;
	using ll = long long;
	typedef pair<int, int> pii;

	vector <int> a = { 0 }, b;
	int nex = 1;

	int count_mushrooms(int n) {

		if (n == 2)
		{
			return 2 - use_machine({0, 1});
		}

		if (n == 3)
		{
			return 3 - use_machine({0, 1}) - use_machine({0, 2});
		}

		bool swapped = false;
		int e = use_machine({0, 1});
		if (e == 1) {
			b.emplace_back(1);
			e = use_machine({0, 2});
			if (e) {
				b.emplace_back(2);
				swapped = true;
				swap(a, b);
			}
			else a.emplace_back(2);
		} else {
			a.emplace_back(1);
		}

		nex = a.size() + b.size();

		int wanted = min(n, (int)77);	

		while (max(a.size(), b.size()) < (size_t)wanted && a.size() + b.size() + max(a.size(), b.size()) < (size_t)n)
		{
			e = use_machine({a[0], nex, a[1], nex + 1});
			
			switch (e)
			{
			case 0:
				a.emplace_back(nex);
				a.emplace_back(nex + 1);

				break;
			
			case 2:
				a.emplace_back(nex + 1);
				b.emplace_back(nex);
				break;
			case 1:
				a.emplace_back(nex);
				b.emplace_back(nex + 1);
				break;
			case 3:
				b.emplace_back(nex);
				b.emplace_back(nex + 1);
				break;

			default:
				assert(0);
			}
			nex += 2;
		}


		if (a.size() + b.size() == (size_t)n) 
		{
			if (swapped) return b.size();
			else return a.size();
		}

		if (b.size() > a.size()) {
			swap(a, b);
			swapped ^= 1;
		}

		int seen = 0;
		int b_count = 0;

		vector <int> v(a.size() * 2), u(b.size() * 2);

		for (size_t i = 0; i < a.size(); i++) v[i * 2] = a[i];
		for (size_t i = 0; i < b.size(); i++) u[i * 2] = b[i];


		while (nex + (int)a.size() < n)
		{
			for (size_t i = 0; i < a.size(); i++) v[i * 2 + 1] = nex++;

			e = use_machine(v);
			b_count += e / 2;

			seen += a.size() - 1;
			if (e & 1)
			{
				b.emplace_back(nex - 1);
				u.emplace_back(nex - 1);
				u.emplace_back(-1);
				if (b.size() > a.size())
				{
					swap(a, b);
					swap(u, v);
					b_count = seen - b_count;
					swapped ^=1;
				}
			} else {
				a.emplace_back(nex - 1);
				v.emplace_back(nex - 1);
				v.emplace_back(-1);
			}
		}
		
		// cout << n << " " <<  nex <<endl;


		int c = nex;
		if (n - nex != 0) {
			vector <int> j((n - nex) * 2);
			for (int i = 0; i < n - c; i++) j[i * 2] = a[i];
			for (int i = 0; i < n - c; i++) j[i * 2 + 1] = nex++;

			e = use_machine(j);
			b_count += e / 2 + (e & 1);
		}
		

		if (swapped) return b_count + b.size();
		else return n - (b_count + b.size());
		
	}

• Subtask 1: 92.623 / 100