BZOJ5465 APIO2018选圆圈（KD-Tree+堆）

　　考虑乱搞，用矩形框圆放KD-Tree上，如果当前删除的圆和矩形有交就递归下去删。为防止被卡，将坐标系旋转一定角度即可。注意eps稍微设大一点，最好开上long double。

#include<iostream>
#include<cstdio>
#include<cmath>
#include<cstdlib>
#include<cstring>
#include<algorithm>
#include<queue>
#include<vector>
using namespace std;
#define ll long long
#define N 300010
#define double long double
char getc(){char c=getchar();while ((c<'A'||c>'Z')&&(c<'a'||c>'z')&&(c<''||c>'')) c=getchar();return c;}
int gcd(int n,int m){return m==?n:gcd(m,n%m);}
int read()
{
    int x=,f=;char c=getchar();
    while (c<''||c>'') {if (c=='-') f=-;c=getchar();}
    while (c>=''&&c<='') x=(x<<)+(x<<)+(c^),c=getchar();
    return x*f;
}
const double PI=acos(-1.0);
const double eps=1E-;
int n,c,cnt,root,ans[N];
struct circle
{
    double d[];int r,i;
    bool operator <(const circle&a) const
    {
        return d[c]<a.d[c];
    }
    void rotate(double alpha)
    {
        double u=d[]*cos(alpha)-d[]*sin(alpha);
        double v=d[]*sin(alpha)+d[]*cos(alpha);
        d[]=u,d[]=v;
    }
}a[N];
struct KDTree{int ch[];double a[][];circle p;
}tree[N];
double sqr(double x){return x*x;}
bool iscross(circle x,circle y){return sqr(x.d[]-y.d[])+sqr(x.d[]-y.d[])<sqr(x.r+y.r)+eps;}
double max(double x,double y,double z){return max(max(x,y),z);}
double iscross(circle p,double a[][]){return sqr(max(p.d[]-a[][],a[][]-p.d[],(double)))+sqr(max(p.d[]-a[][],a[][]-p.d[],(double)))<sqr(p.r)+eps;}
void build(int &k,int l,int r,int op)
{
    if (l>r) return;
    k=++cnt,c=op;int mid=l+r>>;nth_element(a+l,a+mid,a+r+);
    tree[k].p=a[mid];
    tree[k].a[][]=a[mid].d[]-a[mid].r,tree[k].a[][]=a[mid].d[]+a[mid].r,
    tree[k].a[][]=a[mid].d[]-a[mid].r,tree[k].a[][]=a[mid].d[]+a[mid].r;
    for (int i=l;i<=r;i++)
    tree[k].a[][]=min(tree[k].a[][],a[i].d[]-a[i].r),tree[k].a[][]=max(tree[k].a[][],a[i].d[]+a[i].r),
    tree[k].a[][]=min(tree[k].a[][],a[i].d[]-a[i].r),tree[k].a[][]=max(tree[k].a[][],a[i].d[]+a[i].r);
    build(tree[k].ch[],l,mid-,op^);
    build(tree[k].ch[],mid+,r,op^);
}
void find(int k,circle x)
{
    if (!ans[tree[k].p.i]&&iscross(tree[k].p,x)) ans[tree[k].p.i]=x.i;
    if (tree[k].ch[]&&iscross(x,tree[tree[k].ch[]].a)) find(tree[k].ch[],x);
    if (tree[k].ch[]&&iscross(x,tree[tree[k].ch[]].a)) find(tree[k].ch[],x);
}
struct cmp
{
    bool operator ()(const circle&a,const circle&b) const
    {
        return a.r<b.r||a.r==b.r&&a.i>b.i;
    }
};
priority_queue<circle,vector<circle>,cmp> q;
int main()
{
#ifndef ONLINE_JUDGE
    freopen("bzoj5465.in","r",stdin);
    freopen("bzoj5465.out","w",stdout);
    const char LL[]="%I64d\n";
#else
    const char LL[]="%lld\n";
#endif
    n=read();
    for (int i=;i<=n;i++)
    {
        a[i].d[]=read(),a[i].d[]=read(),a[i].i=i,a[i].r=read();
        a[i].rotate(PI/);
        q.push(a[i]);
    }
    build(root,,n,);
    while ()
    {
        while (!q.empty()&&ans[q.top().i]) q.pop();
        if (q.empty()) break;
        circle x=q.top();q.pop();ans[x.i]=x.i;
        find(root,x);
    }
    for (int i=;i<=n;i++) printf("%d ",ans[i]);
    return ;
}