【HDU】1255 覆盖的面积 
  1 #include<cstdio>
  2 #include<cstring>
  3 #include<cstdlib>
  4 #include<cmath>
  5 #include<algorithm>
  6 #define MAXN 5010
  7 #define EPS 1e-8
  8 using namespace std;
  9 struct Line
 10 {
 11     double left,right,high;
 12     int flag;
 13 };
 14 struct node
 15 {
 16     int cover;
 17     double one,more;
 18 };
 19 node tree[MAXN<<2];
 20 Line p[MAXN];
 21 double x[MAXN];
 22 int cmp1(const void *a,const void *b)
 23 {
 24     return (*(Line *)a).high>(*(Line *)b).high?1:-1;
 25 }
 26 int cmp2(const void *a,const void *b)
 27 {
 28     return *(double *)a>*(double *)b?1:-1;
 29 }
 30 inline int dbcmp(double s,double t)
 31 {
 32     if(fabs(s-t)<EPS)
 33         return 0;
 34     return s>t?1:-1;
 35 }
 36 int Bin(double val,int low,int high)
 37 {
 38     int mid,temp;
 39     while(low<high)
 40     {
 41         mid=(low+high)>>1;
 42         temp=dbcmp(x[mid],val);
 43         if(temp==0)
 44             return mid;
 45         if(temp>0)
 46             high=mid;
 47         else
 48             low=mid+1;
 49     }
 50 }
 51 inline void PushUp(int L,int R,int rt)
 52 {
 53     if(tree[rt].cover>1)
 54         tree[rt].one=tree[rt].more=x[R+1]-x[L];
 55     else if(tree[rt].cover==1)
 56     {
 57         tree[rt].one=x[R+1]-x[L];
 58         if(L==R)
 59             tree[rt].more=0;
 60         else
 61             tree[rt].more=tree[rt<<1].one+tree[rt<<1|1].one;
 62     }
 63     else
 64     {
 65         if(L==R)
 66             tree[rt].more=tree[rt].one=0;
 67         else
 68         {
 69             tree[rt].one=tree[rt<<1].one+tree[rt<<1|1].one;
 70             tree[rt].more=tree[rt<<1].more+tree[rt<<1|1].more;
 71         }
 72     }
 73 }
 74 void Update(int s,int t,int val,int L,int R,int rt)
 75 {
 76     if(s<=L&&R<=t)
 77     {
 78         tree[rt].cover+=val;
 79         PushUp(L,R,rt);
 80     }
 81     else
 82     {
 83         int mid=(L+R)>>1;
 84         if(mid>=s)
 85             Update(s,t,val,L,mid,rt<<1);
 86         if(t>mid)
 87             Update(s,t,val,mid+1,R,rt<<1|1);
 88         PushUp(L,R,rt);
 89     }
 90 }
 91 int main()
 92 {
 93     double ans,x1,y1,x2,y2;
 94     int n,i,c,cnt,m,s,t;
 95     scanf("%d",&c);
 96     while(c--)
 97     {
 98         scanf("%d",&n);
 99         for(i=cnt=0;i<n;i++)
100         {
101             scanf("%lf%lf%lf%lf",&x1,&y1,&x2,&y2);
102             if(dbcmp(x1,x2)==0||dbcmp(y1,y2)==0)
103                 continue;
104             if(x1>x2)
105                 swap(x1,x2);
106             if(y1>y2)
107                 swap(y1,y2);
108             p[cnt].flag=1;
109             p[cnt].left=x1;
110             p[cnt].right=x2;
111             x[cnt]=x1;
112             p[cnt++].high=y1;
113             p[cnt].flag=-1;
114             p[cnt].left=x1;
115             p[cnt].right=x2;
116             x[cnt]=x2;
117             p[cnt++].high=y2;
118         }
119         qsort(p,cnt,sizeof(p[0]),cmp1);
120         qsort(x,cnt,sizeof(x[0]),cmp2);
121         for(i=m=0;i<cnt;i++)
122         {
123             if(dbcmp(x[m],x[i]))
124                 x[++m]=x[i];
125         }
126         m++;
127         memset(tree,0,sizeof(tree));
128         for(ans=i=0;i<cnt-1;i++)
129         {
130             s=Bin(p[i].left,0,m);
131             t=Bin(p[i].right,0,m);
132             Update(s,t-1,p[i].flag,0,m-2,1);
133             ans+=(p[i+1].high-p[i].high)*tree[1].more;
134         }
135         printf("%.2lf\n",ans);
136     }
137     return 0;
138 }
posted on 2012-06-09 20:57  DrunBee  阅读(266)  评论(0)  编辑  收藏  举报