Submission #899915

#	Time	Username	Problem	Language	Result	Execution time	Memory
899915		abcvuitunggio	Counting Mushrooms (IOI20_mushrooms)	C++17	100 / 100	5 ms	712 KiB

mushrooms

#include "mushrooms.h"
#include <bits/stdc++.h>
using namespace std;
const int k=100;
vector <int> a[2],ve;
int res,x,c;
void update(){
    if (a[0].size()<a[1].size()){
        swap(a[0],a[1]);
        c^=1;
    }
}
int count_mushrooms(int n){
    if (n<=227){
        for (int i=1;i<n;i++)
            res+=1-use_machine({0,i});
        return res+1;
    }
    a[0].push_back(0);
    for (int i=1;i<3;i++){
        int x=use_machine({0,i});
        a[x].push_back(i);
    }
    update();
    x=use_machine({3,a[0][0],4,a[0][1]});
    a[x&1].push_back(3);
    a[x/2&1].push_back(4);
    update();
    for (int i=5;max(a[0].size(),a[1].size())<k;){
        x=use_machine({i,a[0][0],i+1,a[0][1],i+2,a[0][2]});
        a[x&1].push_back(i);
        if (x/2%2==0){
            a[x/4].push_back(i+1);
            a[x/4].push_back(i+2);
            i+=3;
        }
        else if (a[1].size()<2){
            x=use_machine({a[0][0],i+1});
            a[x].push_back(i+1);
            a[x^1].push_back(i+2);
            i+=3;
        }
        else{
            x=use_machine({i+4,a[0][0],i+3,a[0][1],i+2,a[0][2],a[1][0],i+1,a[1][1]})-1;
            a[x&1].push_back(i+4);
            a[x/2&1].push_back(i+3);
            a[x/4].push_back(i+2);
            a[x/4^1].push_back(i+1);
            i+=5;
        }
    }
    update();
    res=a[1].size();
    for (int i=a[0].size()+a[1].size();i<n;){
        ve.clear();
        int r=min(i+(int)a[0].size(),n);
        for (int j=i;j<r;j++){
            ve.push_back(j);
            ve.push_back(a[0][j-i]);
        }
        x=use_machine(ve);
        res+=(x+1)/2;
        a[x&1].push_back(i);
        if (a[0].size()<a[1].size()){
            res=r-res;
            swap(a[0],a[1]);
            c^=1;
        }
        i=ve[ve.size()-2]+1;
    }
    return (c?res:n-res);
}

• Subtask 1: 100 / 100