Submission #304496

#	Time	Username	Problem	Language	Result	Execution time	Memory
304496		arnold518	Counting Mushrooms (IOI20_mushrooms)	C++14	92.62 / 100	10 ms	508 KiB

mushrooms

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

typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

const int MAXN = 2e4;
const int SQ = 81;

int N;
vector<int> PERM;

int query(vector<int> V)
{
	return use_machine(V);
}

int naive()
{
	int ans=1;
	for(int i=1; i+1<N; i+=2)
	{
		ans+=2-query({i, 0, i+1});
	}
	if(N%2==0) ans+=1-query({0, N-1});
	return ans;
}

int count_mushrooms(int _N)
{
	N=_N;

	if(N<=2*SQ) return naive();

	vector<int> A, B;
	A.push_back(0);

	int p, ans=0;

	for(p=1; p<=2; p++)
	{
		if(query({0, p})) B.push_back(p);
		else A.push_back(p);
	}

	if(A.size()>=2)
	{
		for(; p+1<N && A.size()<SQ && B.size()<SQ; p+=2)
		{
			int t=query({A[0], p, A[1], p+1});
			if(t==0) A.push_back(p), A.push_back(p+1);
			else if(t==1) A.push_back(p), B.push_back(p+1);
			else if(t==2) B.push_back(p), A.push_back(p+1);
			else B.push_back(p), B.push_back(p+1);
		}
	}
	else
	{
		for(; p+1<N && A.size()<SQ && B.size()<SQ; p+=2)
		{
			int t=query({B[0], p, B[1], p+1});
			if(t==0) B.push_back(p), B.push_back(p+1);
			else if(t==1) B.push_back(p), A.push_back(p+1);
			else if(t==2) A.push_back(p), B.push_back(p+1);
			else A.push_back(p), A.push_back(p+1);
		}
	}

	ans=0;

	while(p<N)
	{
		if(A.size()>B.size())
		{
			int i, j;
			vector<int> V;
			for(j=0; p<N && j<A.size(); p++, j++)
			{
				V.push_back(A[j]);
				V.push_back(p);
			}
			int t=query(V);
			if(t%2) B.push_back(V.back());
			else A.push_back(V.back());
			ans+=j-t/2-1;
		}
		else
		{
			int i, j;
			vector<int> V;
			for(j=0; p<N && j<B.size(); p++, j++)
			{
				V.push_back(B[j]);
				V.push_back(p);
			}
			int t=query(V);
			if(t%2) A.push_back(V.back());
			else B.push_back(V.back());
			ans+=t/2;
		}
	}

	return ans+A.size();
}

Compilation message (stderr)

mushrooms.cpp: In function 'int count_mushrooms(int)':
mushrooms.cpp:79:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   79 |    for(j=0; p<N && j<A.size(); p++, j++)
      |                    ~^~~~~~~~~
mushrooms.cpp:77:8: warning: unused variable 'i' [-Wunused-variable]
   77 |    int i, j;
      |        ^
mushrooms.cpp:93:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   93 |    for(j=0; p<N && j<B.size(); p++, j++)
      |                    ~^~~~~~~~~
mushrooms.cpp:91:8: warning: unused variable 'i' [-Wunused-variable]
   91 |    int i, j;
      |        ^

• Subtask 1: 92.623 / 100