Submission #720565

#	Time	Username	Problem	Language	Result	Execution time	Memory
720565		bin9638	Counting Mushrooms (IOI20_mushrooms)	C++17	80.71 / 100	10 ms	516 KiB

mushrooms

#include <bits/stdc++.h>

#ifndef SKY
#include "mushrooms.h"
#endif // SKY

using namespace std;

#define N 100010
#define ll long long
#define fs first
#define sc second
#define ii pair<int,int>
#define pb push_back

#ifdef SKY
int type[N];
int use_machine(vector<int>s)
{
    int res=0;
    for(int i=0;i<s.size()-1;i++)
        res+=(type[s[i]]!=type[s[i+1]]);
    return res;
}
#endif // SKY

int n,hv[N];
vector<int>A,B;

int count_mushrooms(int cc)
{
    n=cc;
    A.clear();
    B.clear();
    A.pb(0);
    int res=1;
    for(int i=0;i<n;i++)
        hv[i]=i;
    random_shuffle(hv+1,hv+n);
    for(int i=1;i<n;)
    {
        if(A.size()>=B.size())
        {
            vector<int>hoi;
            int cnt=0;
            for(int j=i;j<min(n,i+(int)A.size());j++)
            {
                cnt++;
                hoi.pb(hv[j]);
                hoi.pb(A[j-i]);
            }
            int val=(cnt*2-1-use_machine(hoi));
            res+=((val+1)/2);
            if(val&1)
                A.pb(hv[i]);
                    else B.pb(hv[i]);
            i+=(A.size()-(val&1));
        }else
        {
            vector<int>hoi;
            int cnt=0;
            for(int j=i;j<min(n,i+(int)B.size());j++)
            {
                hoi.pb(hv[j]);
                hoi.pb(B[j-i]);
                cnt++;
            }
            int val=(cnt*2-1-use_machine(hoi));
            res+=(cnt-((val+1)/2));
            if(val&1)
                B.pb(hv[i]);
                    else A.pb(hv[i]);
            i+=(B.size()-(val&1));
        }
       // cout<<res<<" "<<i<<endl;
    }
    return res;
}

#ifdef SKY
int main()
{
    freopen("A.inp","r",stdin);
    freopen("A.out","w",stdout);
    ios::sync_with_stdio(0);
    cin.tie(NULL);
    cout.tie(NULL);
    int n;
    cin>>n;
    for(int i=0;i<n;i++)
        cin>>type[i];
    cout<<count_mushrooms(n);
    return 0;
}
#endif

• Subtask 1: 80.7143 / 100