poj 1151 Atlantis (线段树+扫描线）

  1 #include<cstdio>
  2 #include<cstring>
  3 #include<algorithm>
  4 using namespace std;
  5 struct p1
  6 {
  7     double x,y1,y2;
  8     int v;
  9 };p1 str[2010];
 10 bool com(p1 a,p1 b)
 11 {
 12     return a.x<b.x;
 13 }
 14 double y[2010];
 15 struct p2
 16 {
 17     int l,r,c;
 18     double s,ll,rr;
 19 };p2 tree[4100];
 20 void build(int l,int r,int p)
 21 {
 22     tree[p].l=l;tree[p].r=r;
 23     tree[p].s=0;
 24     tree[p].c=0;
 25     tree[p].ll=y[l];
 26     tree[p].rr=y[r];
 27     if (l+1==r) return ;
 28     int m=(l+r)/2;
 29     build(l,m,p*2);
 30     build(m,r,p*2+1);
 31 }
 32 void pushup(int p)
 33 {
 34     if (tree[p].c>0)
 35     {
 36         tree[p].s=tree[p].rr-tree[p].ll;
 37         return ;
 38     }
 39     if (tree[p].l+1==tree[p].r) tree[p].s=0;
 40     else tree[p].s=tree[p*2].s+tree[p*2+1].s;
 41 }
 42 void un(int p,p1 e)
 43 {
 44     if (e.y1==tree[p].ll&&e.y2==tree[p].rr)
 45     {
 46         tree[p].c+=e.v;
 47         pushup(p);
 48         return ;
 49     }
 50     if (e.y2<=tree[p*2].rr) un(p*2,e);
 51     else if (e.y1>=tree[p*2+1].ll) un(p*2+1,e);
 52     else
 53     {
 54         p1 ee=e;
 55         ee.y2=tree[p*2].rr;
 56         un(p*2,ee);
 57         ee=e;
 58         ee.y1=tree[p*2+1].ll;
 59         un(p*2+1,ee);
 60     }
 61     pushup(p);
 62 }
 63 int main()
 64 {
 65     int n,i,j,k=1,t;
 66     double x1,x2,y1,y2,ans;
 67     while (~scanf("%d",&n))
 68     {
 69         t=1;
 70         if (n==0) break;
 71         for (i=1;i<=n;i++)
 72         {
 73             scanf("%lf%lf%lf%lf",&x1,&y1,&x2,&y2);
 74             str[t].x=x1;
 75             str[t].y1=y1;
 76             str[t].y2=y2;
 77             str[t].v=1;
 78             y[t]=y1;
 79             t++;
 80             str[t].x=x2;
 81             str[t].y1=y1;
 82             str[t].y2=y2;
 83             str[t].v=-1;
 84             y[t]=y2;
 85             t++;
 86         }
 87         sort(str+1,str+t,com);
 88         sort(y+1,y+t);
 89         build(1,t-1,1);
 90          ans=0.0;
 91         un(1,str[1]);
 92         for (i=2;i<t;i++)
 93         {
 94             ans+=tree[1].s*(str[i].x-str[i-1].x);
 95             un(1,str[i]);
 96         }
 97         printf("Test case #%d\n",k);
 98         printf("Total explored area: %.2lf\n\n",ans);
 99         k++;
100     }
101 }