Submission #305233

#	Time	Username	Problem	Language	Result	Execution time	Memory
305233		ScarletS	Counting Mushrooms (IOI20_mushrooms)	C++17	92.62 / 100	12 ms	384 KiB

mushrooms

#include "mushrooms.h"
#include <bits/stdc++.h>
#define sz(x) (int)(x).size()
using namespace std;
/**
int N,a[20000],totalQ=0;

int use_machine(vector<int> v)
{
    int k = sz(v), sendBack=0;
    ++totalQ;
    for (int i=1;i<k;++i)
        if (a[v[i]]!=a[v[i-1]])
            ++sendBack;
    return sendBack;
}
**/
const int upkeep=80;

int count_mushrooms(int n) {
    if (n<=226*2)
    {
        int ans=0;
        for (int i = 1; i+1 < n; i+=2)
            ans+=use_machine({i,0,i+1});
        if (!(n&1))
            ans+=use_machine({n-1,0});
        return n-ans;
    }
    else
    {
        vector<int> v={0},w,m;
        int x,y,doneTill=0,k;
        while (max(sz(v),sz(w))<2)
        {
            if (use_machine({0,++doneTill}))
                w.push_back(doneTill);
            else
                v.push_back(doneTill);
        }
        //cout<<sz(v)<<" "<<sz(w)<<"\n";
        while (max(sz(v),sz(w))<upkeep)
        {
            if (sz(v)>sz(w))
            {
                k=use_machine({doneTill+1,v[0],doneTill+2,v[1]});
                if (k&1)
                    w.push_back(doneTill+1);
                else
                    v.push_back(doneTill+1);
                if ((k>>1)&1)
                    w.push_back(doneTill+2);
                else
                    v.push_back(doneTill+2);
            }
            else
            {
                k=use_machine({doneTill+1,w[0],doneTill+2,w[1]});
                if (k&1)
                    v.push_back(doneTill+1);
                else
                    w.push_back(doneTill+1);
                if ((k>>1)&1)
                    v.push_back(doneTill+2);
                else
                    w.push_back(doneTill+2);
            }
            doneTill+=2;
        }
        //cout<<sz(v)<<" "<<sz(w)<<"\n";
        x=sz(v);y=sz(w);
        while (doneTill+1<n)
        {
            m.clear();
            if (sz(v)>sz(w))
            {
                for (int i=doneTill+1;i<=min(doneTill+sz(v),n-1);++i)
                {
                    m.push_back(i);
                    m.push_back(0);
                }
                for (int i=1;i<sz(m);i+=2)
                    m[i]=v[(i>>1)];
                k=use_machine(m);
                if (k&1)
                {
                    w.push_back(m[0]);
                    ++y;
                }
                else
                {
                    v.push_back(m[0]);
                    ++x;
                }
                y+=(k>>1);
                x+=(((sz(m)-1)>>1)-(k>>1));
            }
            else
            {
                for (int i=doneTill+1;i<=min(doneTill+sz(w),n-1);++i)
                {
                    m.push_back(i);
                    m.push_back(0);
                }
                for (int i=1;i<sz(m);i+=2)
                    m[i]=w[(i>>1)];
                k=use_machine(m);
                if (k&1)
                {
                    v.push_back(m[0]);
                    ++x;
                }
                else
                {
                    w.push_back(m[0]);
                    ++y;
                }
                x+=(k>>1);
                y+=(((sz(m)-1)>>1)-(k>>1));
            }
            doneTill=m[sz(m)-2];
        }
        return x;
    }
}
/**
int main()
{
    cin>>N;
    for (int i=0;i<N;++i)
        cin>>a[i];
    cout<<count_mushrooms(N)<<"\n";
    cout<<totalQ<<" queries\n";
}**/

• Subtask 1: 92.623 / 100