Submission #927265

#	Time	Username	Problem	Language	Result	Execution time	Memory
927265		velislavgarkov	Counting Mushrooms (IOI20_mushrooms)	C++14	92.62 / 100	6 ms	712 KiB

mushrooms

#include "mushrooms.h"
#include <iostream>
#include <vector>
#include <cmath>
using namespace std;
int BUCK;
vector <int> br[2], mach;
int find_eq(int n) {
    bool fl=false;
    int start=3, gr=2*BUCK;
    if (n<=300) {
        fl=true;
        gr=n;
    }
    for (int i=3;i<gr;i+=2) {
        if (i==n-1) {
            start=n-1;
            break;
        }
        int type;
        if (br[0].size()>1) type=0;
        else type=1;
        int s=use_machine({i,br[type][0],i+1,br[type][1]});
        if (s==0) {
            br[type].push_back(i);
            br[type].push_back(i+1);
        } else if (s==1) {
            br[!type].push_back(i);
            br[type].push_back(i+1);
        } else if (s==2) {
            br[type].push_back(i);
            br[!type].push_back(i+1);
        } else {
            br[!type].push_back(i);
            br[!type].push_back(i+1);
        }
        start=i+2;
        //if (br[0].size()>BUCK || br[1].size()>BUCK) break;
    }
    if (start==n-1) {
        if (!use_machine({0,n-1})) br[0].push_back(n-1);
        else br[1].push_back(n-1);
    }
    if (fl) start=-1;
    return start;
}
int count_mushrooms(int n) {
    br[0].push_back(0);
    if (!use_machine({0,1})) br[0].push_back(1);
    else br[1].push_back(1);
    if (n==2) return br[0].size();
    if (!use_machine({0,2})) br[0].push_back(2);
    else br[1].push_back(2);
    if (n==3) return br[0].size();

    BUCK=sqrt(n/3);
    int start=find_eq(n);
    if (start==-1) return br[0].size();
    
    int cur, last;
    if (br[0].size()>=br[1].size()) cur=0;
    else cur=1;
    int ans=br[0].size();
    for (int i=start;i<n;i+=last) {
        if (!mach.empty()) mach.clear();
        for (int j=0;j<br[cur].size() && i+j<n;j++) {
            mach.push_back(i+j);
            mach.push_back(br[cur][j]);
        }
        int s=use_machine(mach);
        last=br[cur].size();
        if (s%2==0) br[cur].push_back(i);
        else br[!cur].push_back(i);
        if (cur==1) ans+=(s+1)/2;
        else ans+=mach.size()/2-(s+1)/2;
        if (br[0].size()>=br[1].size()) cur=0;
        else cur=1;
    }
    return ans;
}

Compilation message (stderr)

mushrooms.cpp: In function 'int count_mushrooms(int)':
mushrooms.cpp:66:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   66 |         for (int j=0;j<br[cur].size() && i+j<n;j++) {
      |                      ~^~~~~~~~~~~~~~~

• Subtask 1: 92.623 / 100