hdu3265 矩形面积并

#include<stdio.h>
#include<iostream>
#include<string.h>
#include<algorithm>
#define LL __int64
using namespace std;

const int size=55555;

struct Line
{
int lx,rx,y;
int f;
Line() {}
Line(int a,int b,int c,int d):lx(a),rx(b),y(c),f(d) {}
bool operator < (const Line &cmp) const
{
return y<cmp.y;
}
} line[size<<3];

int cover[size<<4],len[size<<4],X[size<<2];

void PushUp(int rt,int l,int r)
{
if (cover[rt]>0)
len[rt]=X[r+1]-X[l];
else if (l==r) len[rt]=0;
else len[rt]=len[rt<<1]+len[rt<<1|1];
}

void update(int rt,int l,int r,int L,int R,int v)
{
if (L<=l&&r<=R)
{
cover[rt]+=v;
PushUp(rt,l,r);
return ;
}
int m=(l+r)>>1;
if (L<=m) update(rt<<1,l,m,L,R,v);
if (R>m)  update(rt<<1|1,m+1,r,L,R,v);
PushUp(rt,l,r);
}

int Fin(int key,int k)
{
int l=0,r=k;
while (l<=r)
{
int m=(l+r)>>1;
if (X[m]==key) return m;
else if (X[m]<key) l=m+1;
else r=m-1;
}
return -1;
}

int main()
{
int n,m,k,i,L,R;
__int64 ans;
int x1,x2,x3,x4,y1,y2,y3,y4;
while (scanf("%d",&n)&&n)
{
memset(len,0,sizeof(len));
memset(cover,0,sizeof(cover));
for (k=m=i=0; i<n; i++)
{
scanf("%d %d %d %d %d %d %d %d",
&x1,&y1,&x2,&y2,&x3,&y3,&x4,&y4);
X[k++]=x1;  X[k++]=x2;
X[k++]=x3;  X[k++]=x4;
line[m++]=Line(x1,x3,y1,1);
line[m++]=Line(x1,x3,y2,-1);
line[m++]=Line(x3,x4,y1,1);
line[m++]=Line(x3,x4,y3,-1);
line[m++]=Line(x3,x4,y4,1);
line[m++]=Line(x3,x4,y2,-1);
line[m++]=Line(x4,x2,y1,1);
line[m++]=Line(x4,x2,y2,-1);
}
sort(X,X+k);
k=unique(X,X+k)-X-1;
sort(line,line+m);
for (ans=i=0; i<m-1; i++)
{
L=Fin(line[i].lx,k);
R=Fin(line[i].rx,k)-1;
if (L<=R)
update(1,0,k,L,R,line[i].f);
ans+=1ll*len[1]*(line[i+1].y-line[i].y);
}
printf("%I64d\n",ans);
}
return 0;
}