Tsinsen 1485 Catch The Penguins 抓企鹅 ——Bitset

【题目分析】

刚开始想的是KD-Tree去暴力求解。

写了半天还没有暴力得的分数多（说好的nlogn呢）

直接按照四个维度排序。

然后扫一遍，用bitset去维护，然后对于四个维度小于一个询问的结果取一个交就可以了。

Bitset大法好。

【代码】

垃圾KD-Tree

#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <cmath>

#include <set>
#include <map>
#include <string>
#include <algorithm>
#include <vector>
#include <iostream>
#include <queue>

using namespace std;

#define maxn 500005
#define mlog 16
#define F(i,j,k) for (int i=j;i<=k;++i)
#define inf (1e18)

void Finout()
{
    #ifndef ONLINE_JUDGE
    freopen("in.txt","r",stdin);
//    freopen("out.txt","w",stdout);
    #endif
}

struct node{double d[4],mn[4],mx[4];int siz,l,r;}t[maxn],now;
int n,q,D,rt,tot=0,m;
bool operator < (node x,node y){return x.d[D]<y.d[D];}

void update(int k)
{
	F(i,0,3)
	{
		t[k].mx[i]=max(max(t[k].d[i],t[t[k].l].mx[i]),t[t[k].r].mx[i]);
		t[k].mn[i]=min(min(t[k].d[i],t[t[k].l].mn[i]),t[t[k].r].mn[i]);
	}
	t[k].siz=t[t[k].l].siz+t[t[k].r].siz+1;
}

int build(int l,int r,int dir)
{
	int mid=(l+r)/2;
	D=dir;
	nth_element(t+l,t+mid,t+r+1);
	t[mid].siz=1;
	F(i,0,3) t[mid].mx[i]=t[mid].mn[i]=t[mid].d[i];
	t[mid].l=mid>l?build(l,mid-1,(dir+1)%4):0;
	t[mid].r=mid<r?build(mid+1,r,(dir+1)%4):0;
	update(mid);
	return mid;
}

bool in(int o)
{
	int flag=1;
	F(i,0,3)
	{
		{
			if (t[o].mx[i]>=0&&t[o].mx[i]<=now.d[i]);
			else flag=0;
		}
		{
			if (t[o].mn[i]>=0&&t[o].mn[i]<=now.d[i]);
			else flag=0;
		}
	}
	return flag;
}

void print(int o){
    if (!o) return;
    printf("%d t[o].mn[0]=%f t[o].mn[1]=%f t[o].mx[0]=%f t[o].mx[1]=%f  l :%d r: %d\n",o,t[o].mn[0],t[o].mn[1],t[o].mx[0],t[o].mx[1],t[o].l,t[o].r);
    print(t[o].l);
    print(t[o].r);
}

bool din(int o)
{
	int flag=1;
	F(i,0,3)
	{
		if (t[o].d[i]>=0&&t[o].d[i]<=now.d[i]);
		else flag=0;
	}
	return flag;
}

bool out(int o)
{
	int flag=1;
	F(i,0,3)
	{
		if ((t[o].mx[i]>now.d[i]&&t[o].mn[i]>now.d[i])||(t[o].mx[i]<0&&t[o].mn[i]<0));
		else flag=0;
	}
	return flag;
}

int query(int o)
{
	if (!o) return 0;
	if (in(o)){return t[o].siz;}
	else
	{
		int ret=0;
		if (din(o)) ret+=1;
		if (t[o].l)
		{
			if (out(t[o].l)); else ret+=query(t[o].l);
		}
		if (t[o].r)
		{
			if (out(t[o].r)); else ret+=query(t[o].r);
		}
		return ret;
	}
}

int main()
{
	Finout();
	F(i,0,3) t[0].mx[i]=inf,t[0].mn[i]=-inf;
	scanf("%d",&m);n=1;
	F(i,1,m)
	{
		int flag=1;
		F(j,0,3)
		{
			scanf("%lf",&t[n].d[j]);
			if (t[n].d[j]<0) flag=0;
		}
		if (flag) n++;
	}
	n--;
	rt=build(1,n,1);
	scanf("%d",&q);
	F(i,1,q)
	{
		int flag=1;
		F(j,0,3)
		{
			scanf("%lf",&now.d[j]);
			if (now.d[j]<0) flag=0;
		}
		if (flag) printf("%d\n",query(rt));
		else printf("0\n");
	}
}

有趣的Bitset

#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <cmath>
#include <set>
#include <map>
#include <bitset>
#include <string>
#include <algorithm>
#include <vector>
#include <iostream>
#include <queue>
using namespace std;
#define maxn 30010
#define F(i,j,k) for (int i=j;i<=k;++i)
int Getint()
{
    int x=0,f=1; char ch=getchar();
    while (ch<'0'||ch>'9') {if (ch=='-') f=-1; ch=getchar();}
    while (ch>='0'&&ch<='9') {x=x*10+ch-'0'; ch=getchar();}
    return x*f;
}
bitset<maxn> b[maxn],now;
struct node{double d[4];int id;}a[maxn],q[maxn];
int n,m,D;
bool cmp(node x,node y){return x.d[D]<y.d[D];}
int main()
{
    scanf("%d",&n);
    F(i,1,n)
    {
        scanf("%lf%lf%lf%lf",&a[i].d[0],&a[i].d[1],&a[i].d[2],&a[i].d[3]);
        a[i].id=i;
    }
    scanf("%d",&m);
    F(i,1,m)
    {
        scanf("%lf%lf%lf%lf",&q[i].d[0],&q[i].d[1],&q[i].d[2],&q[i].d[3]);
        q[i].id=i;
        b[i].set();
    }
    F(i,0,3)
    {
        D=i;
        sort(a+1,a+n+1,cmp);
        sort(q+1,q+m+1,cmp);
        now.reset();
        int p=1;
        F(j,1,m)
        {
            while (p<=n&&a[p].d[i]<=q[j].d[i]) now[a[p].id]=1,p++;
            b[q[j].id]&=now;
        }
    }
    F(i,1,m) printf("%d\n",b[i].count());
}