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 }

View Code