Submission #605063

#	Time	Username	Problem	Language	Result	Execution time	Memory
605063		SamAnd	Counting Mushrooms (IOI20_mushrooms)	C++17	91.87 / 100	9 ms	516 KiB

mushrooms

#include "mushrooms.h"
#include <bits/stdc++.h>
using namespace std;
#define fi first
#define se second
#define all(x) (x).begin(),(x).end()
#define sz(x) ((int)(x).size())
#define m_p make_pair
typedef long long ll;
mt19937 rnf(234);
const int M = 200;

int count_mushrooms(int n)
{
    vector<int> v;
    for (int i = 1; i < min(n, M); ++i)
        v.push_back(i);

    vector<int> a;
    vector<int> b;
    a.push_back(0);
    while (!v.empty())
    {
        if (sz(v) == 1 || (max(sz(a), sz(b)) < 2))
        {
            int q = use_machine({0, v.back()});
            if (q == 0)
                a.push_back(v.back());
            else
                b.push_back(v.back());
            v.pop_back();
            continue;
        }
        if (sz(a) >= 2)
        {
            int q = use_machine({a[0], v[0], a[1], v[1]});
            if (q == 0)
            {
                a.push_back(v[0]);
                a.push_back(v[1]);
            }
            else if (q == 3)
            {
                b.push_back(v[0]);
                b.push_back(v[1]);
            }
            else if (q == 1)
            {
                a.push_back(v[0]);
                b.push_back(v[1]);
            }
            else if (q == 2)
            {
                b.push_back(v[0]);
                a.push_back(v[1]);
            }
        }
        else
        {
            int q = use_machine({b[0], v[0], b[1], v[1]});
            if (q == 0)
            {
                b.push_back(v[0]);
                b.push_back(v[1]);
            }
            else if (q == 3)
            {
                a.push_back(v[0]);
                a.push_back(v[1]);
            }
            else if (q == 1)
            {
                b.push_back(v[0]);
                a.push_back(v[1]);
            }
            else if (q == 2)
            {
                a.push_back(v[0]);
                b.push_back(v[1]);
            }
        }
        reverse(all(v));
        v.pop_back();
        v.pop_back();
    }

    int ans = sz(a);

    for (int i = M; i < n; ++i)
        v.push_back(i);
    while (!v.empty())
    {
        if (sz(a) > sz(b))
        {
            if (sz(v) <= sz(a))
            {
                vector<int> x;
                for (int i = 0; i < sz(v); ++i)
                {
                    x.push_back(a[i]);
                    x.push_back(v[i]);
                }
                int q = use_machine(x);
                ans += (sz(v) - 1 - q / 2);
                if (q % 2 == 0)
                {
                    ++ans;
                    a.push_back(v.back());
                }
                else
                {
                    b.push_back(v.back());
                }
                v.clear();
            }
            else
            {
                vector<int> u;
                for (int i = 0; i < sz(a); ++i)
                {
                    u.push_back(v.back());
                    v.pop_back();
                }

                vector<int> x;
                for (int i = 0; i < sz(u); ++i)
                {
                    x.push_back(a[i]);
                    x.push_back(u[i]);
                }
                int q = use_machine(x);
                ans += (sz(u) - 1 - q / 2);
                if (q % 2 == 0)
                {
                    ++ans;
                    a.push_back(u.back());
                }
                else
                {
                    b.push_back(u.back());
                }
                u.clear();
            }
        }
        else
        {
            if (sz(v) <= sz(b))
            {
                vector<int> x;
                for (int i = 0; i < sz(v); ++i)
                {
                    x.push_back(b[i]);
                    x.push_back(v[i]);
                }
                int q = use_machine(x);
                ans += q / 2;
                if (q % 2 == 0)
                {
                    b.push_back(v.back());
                }
                else
                {
                    ++ans;
                    a.push_back(v.back());
                }
                v.clear();
            }
            else
            {
                vector<int> u;
                for (int i = 0; i < sz(b); ++i)
                {
                    u.push_back(v.back());
                    v.pop_back();
                }

                vector<int> x;
                for (int i = 0; i < sz(u); ++i)
                {
                    x.push_back(b[i]);
                    x.push_back(u[i]);
                }
                int q = use_machine(x);
                ans += q / 2;
                if (q % 2 == 0)
                {
                    b.push_back(u.back());
                }
                else
                {
                    ++ans;
                    a.push_back(u.back());
                }
                u.clear();
            }
        }
    }

    return ans;
}

• Subtask 1: 91.8699 / 100