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

这道题和1151一样嘛！自己有打一边温习温习

详细讲解看 

http://blog.csdn.net/youngyangyang04/article/details/7787693

#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;
    }
}