Submission #306963

#	Time	Username	Problem	Language	Result	Execution time	Memory
306963		baluteshih	Counting Mushrooms (IOI20_mushrooms)	C++14	99.56 / 100	10 ms	580 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;
#define X first
#define Y second
#define ALL(v) v.begin(),v.end()
#define pb push_back
#define SZ(a) ((int)a.size())

const int K=80;

int count_mushrooms(int n)
{
    int ans=0;
    if(n<=227)
    {
        ++ans;
        for(int i=1;i<n;++i)
            ans+=(use_machine({0,i})==0);
        return ans;
    }
    srand(time(NULL));
    vector<int> num(n-1,0);
	vector<int> a(1,0),b;
    for(int i=0;i+1<n;++i)
        num[i]=i+1;
    random_shuffle(ALL(num));
    for(int i=0;i<2;++i)
        if(use_machine({0,num[i]})==0)
            a.pb(num[i]);
        else
            b.pb(num[i]);
    if(SZ(a)>SZ(b))
    {
        int x=use_machine({a[0],num[2],a[1],num[3]});
        if(x==0)
            a.pb(num[2]),a.pb(num[3]);
        else if(x==1)
            a.pb(num[2]),b.pb(num[3]);
        else if(x==2)
            a.pb(num[3]),b.pb(num[2]);
        else
            b.pb(num[2]),b.pb(num[3]);
    }
    else
    {
        int x=use_machine({b[0],num[2],b[1],num[3]});
        if(x==0)
            b.pb(num[2]),b.pb(num[3]);
        else if(x==1)
            b.pb(num[2]),a.pb(num[3]);
        else if(x==2)
            b.pb(num[3]),a.pb(num[2]);
        else
            a.pb(num[2]),a.pb(num[3]);
    }
    vector<int> tmp;
    for(int i=4,j=0;i+2<SZ(num)&&j<K;++j)
    {
        int x;
        if(SZ(a)>=3)
        {
            if(!tmp.empty())
            {
                x=use_machine({a[0],tmp.back(),a[1],num[i],a[2],num[i+1]});
                if(x&1)
                    b.pb(num[i+1]);
                else
                    a.pb(num[i+1]);
                if(x<=1||x>=4)
                {
                    for(int nw=(x>=4);!tmp.empty();nw^=1,tmp.pop_back())
                        if(nw==0)
                            a.pb(tmp.back());
                        else
                            b.pb(tmp.back());
                    if(x<=1)
                        a.pb(num[i]);
                    else
                        b.pb(num[i]);
                }
                else
                    tmp.pb(num[i]);
                i+=2;
            }
            else
            {
                x=use_machine({a[0],num[i],a[1],num[i+1],a[2],num[i+2]});
                if(x&1)
                    b.pb(num[i+2]);
                else
                    a.pb(num[i+2]);
                if(x<=1)
                    a.pb(num[i]),a.pb(num[i+1]);
                else if(x>=4)
                    b.pb(num[i]),b.pb(num[i+1]);
                else
                    tmp.pb(num[i]),tmp.pb(num[i+1]);
                i+=3;
            }
        }
        else
        {
            if(!tmp.empty())
            {
                x=use_machine({b[0],tmp.back(),b[1],num[i],b[2],num[i+1]});
                if(x&1)
                    a.pb(num[i+1]);
                else
                    b.pb(num[i+1]);
                if(x<=1||x>=4)
                {
                    for(int nw=(x>=4);!tmp.empty();nw^=1,tmp.pop_back())
                        if(nw==0)
                            b.pb(tmp.back());
                        else
                            a.pb(tmp.back());
                    if(x<=1)
                        b.pb(num[i]);
                    else
                        a.pb(num[i]);
                }
                else
                    tmp.pb(num[i]);
                i+=2;
            }
            else
            {
                x=use_machine({b[0],num[i],b[1],num[i+1],b[2],num[i+2]});
                if(x&1)
                    a.pb(num[i+2]);
                else
                    b.pb(num[i+2]);
                if(x<=1)
                    b.pb(num[i]),b.pb(num[i+1]);
                else if(x>=4)
                    a.pb(num[i]),a.pb(num[i+1]);
                else
                    tmp.pb(num[i]),tmp.pb(num[i+1]);
                i+=3;
            }
        }
    }
    if(!tmp.empty())
    {
        for(int nw=use_machine({0,tmp.back()});!tmp.empty();nw^=1,tmp.pop_back())
            if(nw==0)
                a.pb(tmp.back());
            else
                b.pb(tmp.back());
    }
    ans=SZ(a);
    int nw=SZ(a)+SZ(b)-1;
    while(nw+max(SZ(a),SZ(b))<=SZ(num))
    {
        if(SZ(a)>=SZ(b))
        {
            int q=SZ(a);
            vector<int> tmp;
            for(int j=0;j<q;++j)
                tmp.pb(a[j]),tmp.pb(num[nw+j]);
            int x=use_machine(tmp);
            if(x&1)
                --x,b.pb(num[nw+q-1]);
            else
                ++ans,a.pb(num[nw+q-1]);
            ans+=((q-1)*2-x)/2;
            nw+=q;
        }
        else
        {
            int q=SZ(b);
            vector<int> tmp;
            for(int j=0;j<q;++j)
                tmp.pb(b[j]),tmp.pb(num[nw+j]);
            int x=use_machine(tmp);
            if(x&1)
                ++ans,--x,a.pb(num[nw+q-1]);
            else
                b.pb(num[nw+q-1]);
            ans+=x/2;
            nw+=q;
        }
    }
    if(nw<SZ(num))
    {
        if(SZ(a)>=SZ(b))
        {
            vector<int> tmp;
            for(int j=0;nw+j<SZ(num);++j)
                tmp.pb(a[j]),tmp.pb(num[nw+j]);
            tmp.pb(a.back());
            int x=use_machine(tmp);
            ans+=((SZ(num)-nw)*2-x)/2;
        }
        else
        {
            vector<int> tmp;
            for(int j=0;nw+j<SZ(num);++j)
                tmp.pb(b[j]),tmp.pb(num[nw+j]);
            tmp.pb(b.back());
            int x=use_machine(tmp);
            ans+=x/2;
        }
    }
    return ans;
}

• Subtask 1: 99.5595 / 100