POJ1151 Atlantis 水题 计算几何

http://poj.org/problem?id=1151

想学一下扫描线线段树，结果写了道水题。

 #include<iostream>
 #include<cstdio>
 #include<algorithm>
 #include<cstring>
 #include<cmath>
 #include<set>
 using namespace std;
 const int maxn=;
 int n;
 double a1[maxn][];
 int a[maxn][];
 double b[maxn*],c[maxn*];
 int tot=,tot1=;
 int main(){
     for(int T=;;T++){
         scanf("%d",&n);
         if(n==)break;
         tot=,tot1=;
         for(int i=;i<=n;i++){
             scanf("%lf%lf%lf%lf",&a1[i][],&a1[i][],&a1[i][],&a1[i][]);
             b[++tot]=a1[i][];b[++tot]=a1[i][];
             c[++tot1]=a1[i][];c[++tot1]=a1[i][];
         }
         sort(b+,b++tot);sort(c+,c++tot1);
         tot=unique(b+,b++tot)-b-;
         tot1=unique(c+,c++tot1)-c-;
         for(int i=;i<=n;i++){
             a[i][]=lower_bound(b+,b++tot,a1[i][])-b;
             a[i][]=lower_bound(c+,c++tot1,a1[i][])-c;
             a[i][]=lower_bound(b+,b++tot,a1[i][])-b;
             a[i][]=lower_bound(c+,c++tot1,a1[i][])-c;
         }double ans=;
         for(int i=;i<tot;i++){
             for(int j=;j<tot1;j++){
                 int f=;
                 for(int z=;z<=n;z++){
                     if(i+<=a[z][]&&i>=a[z][]&&j+<=a[z][]&&j>=a[z][]){
                         f=;break;
                     }
                 }
                 if(f){
                     ans+=(b[i+]-b[i])*(c[j+]-c[j]);
                 }
             }
         }
         printf("Test case #%d\n",T);
         printf("Total explored area: %.2f\n\n",ans);
     }
     return ;
 }