poj 1389 Area of Simple Polygons 线段树扫面线，和1151一样的嘛

#include<iostream>
#include<stdio.h>
#include<algorithm>
using namespace std;
#define N 1005
struct ode{
int y1,y2,x,flag;
}node[N*3];
bool cmp(ode a,ode b){
return a.x<b.x;
}
int y[N*2],pa[N*2];
struct Node{
int l;int r;int s;int ml,mr,len;
}a[N*6];
void build(int i,int left,int right){
a[i].l=left;
a[i].r=right;
a[i].len=0;
a[i].s=0;a[i].mr=y[a[i].r];a[i].ml=y[a[i].l];
if(a[i].r==a[i].l+1) return ;
int mid=(left+right)>>1;
build(i*2,left,mid);
build(i*2+1,mid,right);
}
int len(int i){
if(a[i].s>0){
return a[i].mr-a[i].ml;
}else if(a[i].r==a[i].l+1){
return 0;
}else{
return a[i*2].len+a[i*2+1].len;
}
}
void insert(int i,ode m){
if(pa[a[i].l]==m.y1&&pa[a[i].r]==m.y2){
a[i].s+=m.flag;
a[i].len=len(i);
return ;
}
if(m.y2<=pa[a[i*2].r]) insert(i*2,m);
else if(m.y1>=pa[a[i*2+1].l]) insert(i*2+1,m);
else{
ode temp=m;
temp.y2=pa[a[i*2].r];
insert(i*2,temp);
temp=m;
temp.y1=pa[a[i*2+1].l];
insert(i*2+1,temp);
}
a[i].len=len(i);
}
int main(){
//    freopen("in.txt","r",stdin);
int x1,y1,x2,y2;
int t=1;
while(~scanf("%d%d%d%d",&x1,&y1,&x2,&y2)){
if(x1==-1&&x2==-1&&y1==-1&&y2==-1){
//            cout<<t<<endl;
if(t==1) continue;
sort(y+1,y+t);
for(int i=1;i<t;i++)
pa[i]=y[i];
sort(node+1,node+t,cmp);
build(1,1,t-1);
insert(1,node[1]);
int sum=0;
for(int i=2;i<t;i++){
sum+=(node[i].x-node[i-1].x)*a[1].len;
insert(1,node[i]);
}
printf("%d\n",sum);
t=1;
continue;
}
node[t].y1=y1;
node[t].y2=y2;
node[t].x=x1;
node[t].flag=1;
y[t++]=y1;
node[t].y1=y1;
node[t].y2=y2;
node[t].x=x2;
node[t].flag=-1;
y[t++]=y2;
}
}