hdu 1255 覆盖的面积

http://acm.hdu.edu.cn/showproblem.php?pid=1255

  1 #include <cstdio>
  2 #include <cstring>
  3 #include <algorithm>
  4 #define maxn 100010
  5 using namespace std;
  6 
  7 int t,n;
  8 double Y[maxn],X[maxn];
  9 struct point
 10 {
 11     double x;
 12     double y_up;
 13     double y_down;
 14     int lr;
 15     bool operator <(const point &a) const
 16     {
 17         return x<a.x;
 18     }
 19 }p[maxn*4];
 20 
 21 struct node
 22 {
 23     double x;
 24     double y_up;
 25     double y_down;
 26     int cover;
 27     bool flag;
 28 }tree[maxn*4];
 29 
 30 void build(int i,int l,int r)
 31 {
 32     tree[i].x=-1;
 33     tree[i].y_up=Y[r];
 34     tree[i].y_down=Y[l];
 35     tree[i].cover=0;
 36     tree[i].flag=true;
 37     if(l+1==r)
 38     {
 39         tree[i].flag=false;
 40         return ;
 41     }
 42     int mid=(l+r)>>1;
 43     build(i<<1,l,mid);
 44     build(i<<1|1,mid,r);
 45 }
 46 
 47 double update(int i,double l,double r,double x,int lr)
 48 {
 49     if(tree[i].y_down>=r||tree[i].y_up<=l) return 0;
 50     if(!tree[i].flag)
 51     {
 52         if(tree[i].cover>1)
 53         {
 54             tree[i].cover+=lr;
 55             double sum=(x-tree[i].x)*(tree[i].y_up-tree[i].y_down);
 56             tree[i].x=x;
 57             return sum;
 58         }
 59         else
 60         {
 61             tree[i].cover+=lr;
 62             tree[i].x=x;
 63             return 0;
 64         }
 65     }
 66     else return update(i<<1,l,r,x,lr)+update(i<<1|1,l,r,x,lr);
 67 }
 68 int main()
 69 {
 70     scanf("%d",&t);
 71     while(t--)
 72     {
 73         scanf("%d",&n);
 74         int cnt=0;
 75         for(int i=1; i<=n; i++)
 76         {
 77             double x1,y1,x2,y2;
 78             scanf("%lf%lf%lf%lf",&x1,&y1,&x2,&y2);
 79             p[cnt].x=x1;
 80             p[cnt].y_down=y1;
 81             p[cnt].y_up=y2;
 82             p[cnt].lr=1;
 83             X[cnt]=x1;
 84             Y[cnt++]=y1;
 85             p[cnt].x=x2;
 86             p[cnt].y_down=y1;
 87             p[cnt].y_up=y2;
 88             X[cnt]=x2;
 89             p[cnt].lr=-1;
 90             Y[cnt++]=y2;
 91         }
 92         sort(Y,Y+cnt);
 93         sort(X,X+cnt);
 94         sort(p,p+cnt);
 95         build(1,0,cnt-1);
 96         double ans=0;
 97         for(int i=0; i<cnt; i++)
 98         {
 99             ans+=update(1,p[i].y_down,p[i].y_up,p[i].x,p[i].lr);
100         }
101         printf("%.2lf\n",ans);
102     }
103     return 0;
104 }
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posted @ 2014-08-16 10:31  null1019  阅读(128)  评论(0)  编辑  收藏  举报