Submission #1055649

#	Time	Username	Problem	Language	Result	Execution time	Memory
1055649		pcc	Counting Mushrooms (IOI20_mushrooms)	C++17	72.67 / 100	9 ms	852 KiB

mushrooms

#include "mushrooms.h"
#include <bits/stdc++.h>
using namespace std;
 
const int B = 130;
//const int B = 3;
 
vector<int> perm;
 
int ask(vector<int> v){
	//for(auto &i:v)i = perm[i];
	return use_machine(v);
}
 
int count_mushrooms(int n) {
	if(n<=B*2){
		int ans = 1;
		for(int i = 1;i<n;i++){
			int re = use_machine(vector<int>({0,i}));
			if(!re)ans++;
		}
		return ans;
	}
	srand(time(NULL));
	for(int i = 0;i<n;i++)perm.push_back(i);
	random_shuffle(perm.begin()+1,perm.end());
  ask(perm);
	vector<int> v[2];
	v[0].push_back(0);
	int nxt = 1;
	for(int i = 1;max(v[0].size(),v[1].size())<B;i++){
		int re = ask(vector<int>({0,i*3-2,i*3-1,i*3}));
		if(re == 0){
			v[0].push_back(i*3-2);
			v[0].push_back(i*3-1);
			v[0].push_back(i*3);
		}
		else if(re == 3){
			v[1].push_back(i*3-2);
			v[0].push_back(i*3-1);
			v[1].push_back(i*3);
		}
		else if(re == 1){
			v[1].push_back(i*3);
			re = ask(vector<int>({0,i*3,i*3-2,i*3-1}));
			if(re == 1){
				v[1].push_back(i*3-2);
				v[1].push_back(i*3-1);
			}
			else if(re == 2){
				v[0].push_back(i*3-2);
				v[0].push_back(i*3-1);
			}
			else if(re == 3){
				v[0].push_back(i*3-2);
				v[1].push_back(i*3-1);
			}
			else assert(false);
		}
		else if(re == 2){
			v[0].push_back(i*3);
			int re = ask(vector<int>({i*3-2,0,i*3-1,i*3}));
			if(re == 2){
				v[0].push_back(i*3-2);
				v[1].push_back(i*3-1);
			}
			else if(re == 3){
				v[1].push_back(i*3-2);
				v[1].push_back(i*3-1);
			}
			else if(re == 1){
				v[1].push_back(i*3-2);
				v[0].push_back(i*3-1);
			}
			else assert(false);
		}
		nxt = i*3+1;
	}
	int dir = (v[0].size()<v[1].size());
	int cnt[2] = {v[0].size(),v[1].size()};
	/*
	cerr<<"DIR: "<<dir<<endl;for(auto &i:v[dir])cerr<<i<<',';cerr<<endl;
	cerr<<"NXT: "<<nxt<<endl;
	*/
	for(int i = nxt;i<n;i+=v[dir].size()){
		vector<int> vv;
		for(int j = i;j<min(n,i+(int)v[dir].size());j++)vv.push_back(j);
		//cerr<<"VV: ";for(auto &j:vv)cerr<<j<<',';cerr<<endl;
		vector<int> req;
		for(int j = 0;j<vv.size();j++){
			req.push_back(v[dir][j]);
			req.push_back(vv[j]);
		}
		//cerr<<nxt<<','<<vv.size()<<":"<<endl;for(auto &j:req)cerr<<j<<',';cerr<<endl;
		int re = ask(req);
		if(re&1)re++;
		re>>=1;
		cnt[dir^1] += re;
		cnt[dir] += vv.size()-re;
	}
	return cnt[0];
}

Compilation message (stderr)

mushrooms.cpp: In function 'int count_mushrooms(int)':
mushrooms.cpp:80:25: warning: narrowing conversion of 'v[0].std::vector<int>::size()' from 'std::vector<int>::size_type' {aka 'long unsigned int'} to 'int' [-Wnarrowing]
   80 |  int cnt[2] = {v[0].size(),v[1].size()};
      |                ~~~~~~~~~^~
mushrooms.cpp:80:37: warning: narrowing conversion of 'v[1].std::vector<int>::size()' from 'std::vector<int>::size_type' {aka 'long unsigned int'} to 'int' [-Wnarrowing]
   80 |  int cnt[2] = {v[0].size(),v[1].size()};
      |                            ~~~~~~~~~^~
mushrooms.cpp:90:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   90 |   for(int j = 0;j<vv.size();j++){
      |                 ~^~~~~~~~~~

• Subtask 1: 72.6688 / 100