Submission #1179875

#	Time	Username	Problem	Language	Result	Execution time	Memory
1179875		simona1230	IOI Fever (JOI21_fever)	C++20	19 / 100	5094 ms	456 KiB

fever

#include <bits/stdc++.h>

using namespace std;

struct point
{
    long long x,y;
    point(){}
    point(long long _x,long long _y)
    {
        x=_x;
        y=_y;
    }
};

long long n;
point p[200001];

void read()
{
    cin>>n;
    for(long long i=1;i<=n;i++)
        cin>>p[i].x>>p[i].y;
}

vector<pair<long long,long long> > v[401];

long long num(long long pt,long long d)
{
    if(d==1&&p[pt].y>p[1].y)return -1;
    if(d==2&&p[pt].x>p[1].x)return -1;
    if(d==3&&p[pt].y<p[1].y)return -1;
    if(d==4&&p[pt].x<p[1].x)return -1;
    return (d-1)*n+pt;
}

void ae(long long x,long long y,long long z)
{
    if(x==-1||y==-1)return;
    v[x].push_back({y,z});
    v[y].push_back({x,z});
}

void build()
{
    for(long long i=1;i<=n;i++)
    {
        for(long long j=1;j<=n;j++)
        {
            if(i==j||p[i].x>p[j].x)continue;

            point a=p[i],b=p[j];

            long long z=abs(a.x-b.x);
            if(b.x-a.x==b.y-a.y)
            {
                long long x=num(i,2),y=num(j,3);
                //cout<<i<<" "<<j<<" "<<x<<" "<<y<<endl;
                ae(x,y,z);
                x=num(i,1),y=num(j,4);
                //cout<<i<<" "<<j<<" "<<x<<" "<<y<<endl;
                ae(x,y,z);
            }

            if(b.x-a.x==a.y-b.y)
            {
                long long x=num(i,3),y=num(j,4);
                //cout<<i<<" "<<j<<" "<<x<<" "<<y<<endl;
                ae(x,y,z);
                x=num(i,2),y=num(j,1);
                //cout<<i<<" "<<j<<" "<<x<<" "<<y<<endl;
                ae(x,y,z);
            }
        }
    }
}

long long cnt=0,in[401],used[401];

void bfs(long long s)
{
    priority_queue<pair<long long,long long> > q;
    q.push({0,s});
    used[s]=0;
    cnt=1;
    while(q.size())
    {
        pair<long long,long long> t=q.top();
        //cout<<t.second<<" "<<t.first<<endl;
        q.pop();
        for(long long i=0;i<v[t.second].size();i++)
        {
            pair<long long,long long> nb=v[t.second][i];
            if(used[nb.first]>nb.second&&nb.second>=t.first&&in[nb.first])
            {
                if(used[nb.first]==1e9+1)cnt++;
                used[nb.first]=nb.second;
                q.push({nb.second,nb.first});
            }
        }
    }
    //cout<<cnt<<" !!"<<endl;
}

long long f,ans;
void rec(long long i)
{
    if(i==n+1)
    {
        cnt=0;
        for(long long j=1;j<=4*n;j++)
            used[j]=1e9+1;
        bfs(f);
        ans=max(ans,cnt);

        return;
    }

    for(long long d=1;d<=4;d++)
    {
        if(num(i,d)==-1)continue;
        if(i==1)f=num(1,d);
        in[num(i,d)]=1;
        rec(i+1);
        in[num(i,d)]=0;
    }
}

int main()
{
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	cout.tie(NULL);
	read();
	if(p[1].x==0&&p[1].y==0)
        {
            ans=1;
            for(int i=2;i<=n;i++)
                if(p[i].x==p[i].y)ans++;
            cout<<ans<<endl;
            return 0;
        }
	build();
	rec(1);
	cout<<ans<<endl;
	return 0;
}
/*
3
0 0
3 3
-1 7

*/

• Subtask 1: 5 / 5
• Subtask 2: 8 / 8
• Subtask 3: 6 / 6
• Subtask 4: 0 / 6
• Subtask 5: 0 / 12
• Subtask 6: 0 / 32
• Subtask 7: 0 / 31