Submission #308384

#	Time	Username	Problem	Language	Result	Execution time	Memory
308384		CodePlatina	Counting Mushrooms (IOI20_mushrooms)	C++14	87.94 / 100	9 ms	512 KiB

mushrooms

#include "mushrooms.h"
#include <vector>

using namespace std;

int count_mushrooms(int n)
{
    if(n <= 452)
    {
        int ret = 1;
        for(int i = 1; i < n; i += 2)
        {
            if(i == n - 1) ret += 1 - use_machine({0, i});
            else ret += 2 - use_machine({i, 0, i + 1});
        }
        return ret;
    }
    else
    {
        int ret = 0;
        vector<int> A, B, C;
        A.push_back(0);
        for(int i = 1; i < n; ++i) C.push_back(i);
        while(A.size() < 141 && B.size() < 141)
        {
            if(A.size() >= 2)
            {
                int x = C.back(); C.pop_back();
                int y = C.back(); C.pop_back();
                int t = use_machine({A[0], x, A[1], y});
                if(t & 1) B.push_back(y);
                else A.push_back(y);
                if(t / 2) B.push_back(x);
                else A.push_back(x);
            }
            else if(B.size() >= 2)
            {
                int x = C.back(); C.pop_back();
                int y = C.back(); C.pop_back();
                int t = use_machine({B[0], x, B[1], y});
                if(t & 1) A.push_back(y);
                else B.push_back(y);
                if(t / 2) A.push_back(x);
                else B.push_back(x);
            }
            else
            {
                int x = C.back(); C.pop_back();
                int t = use_machine({A[0], x});
                if(t) B.push_back(x);
                else A.push_back(x);
            }
        }
        while(C.size())
        {
            if(A.size() >= B.size())
            {
                int cnt = -1;
                vector<int> tmp;
                for(int i = 0; (int)C.size() && i < (int)A.size(); ++i)
                {
                    ++cnt;
                    tmp.push_back(A[i]);
                    tmp.push_back(C.back());
                    C.pop_back();
                }
                int t = use_machine(tmp);
                if(t & 1) --t, B.push_back(tmp.back());
                else A.push_back(tmp.back());
                ret += cnt - t / 2;
            }
            else
            {
                int cnt = -1;
                vector<int> tmp;
                for(int i = 0; (int)C.size() && i < (int)B.size(); ++i)
                {
                    ++cnt;
                    tmp.push_back(B[i]);
                    tmp.push_back(C.back());
                    C.pop_back();
                }
                int t = use_machine(tmp);
                if(t & 1) --t, A.push_back(tmp.back());
                else B.push_back(tmp.back());
                ret += t / 2;
            }
        }
        return ret + A.size();
    }
}

• Subtask 1: 87.9377 / 100