***hdu6354 Everything Has Changed(计算几何)
``
#include <math.h>
#include <stdio.h>
using namespace std;
double pi=3.1415926545;
int m;double r;
double ans;
double abss(double k){
return k>=0?k:-k;
}
struct Node{
double r;
double x,y;
}circle[150];
bool rig(Node a){
double rl=(r+a.r)*(r+a.r);
double rr=(r-a.r)*(r-a.r);
if(a.x*a.x+a.y*a.y==rr){
ans+=2.0*pi*a.r;
return false;
}
if(a.x*a.x+a.y*a.y<rl&&a.x*a.x+a.y*a.y>rr)
return true;
return false;
}
void torun(Node a){
double l=sqrt(a.x*a.x+a.y*a.y);
double xita1=(r*r+l*l-a.r*a.r)/(2*r*l);//余弦距离求两个圆心角
double xita2=(a.r*a.r+l*l-r*r)/(2*a.r*l);
xita1=2*acos(xita1);
xita2=2*acos(xita2);
ans-=r*xita1;
ans+=a.r*xita2;
}
int main()
{
int t;
cin>>t;
int i,j,k;
while(t--){
ans=0;
cin>>m>>r;
ans=2.0*pi*r;
for(i=1;i<=m;i++){
cin>>circle[i].x>>circle[i].y>>circle[i].r;
if(rig(circle[i])){
torun(circle[i]);
}//cout<<ans<<endl;
}
printf("%.8f\n",ans);
}
return 0;
}