POJ3129计算几何水题

大意：n个星星给出空间中坐标。m个望远镜在原点给出视野中心的一个点和视角pi。求有几个星星能被看到，n,m<=500.

1A，直接用向量计算cos(0-星星，0-望远镜中心)>=pi即可。注意精度处理。

program p3129;
var
 x,y,z,x2,y2,z2,pi:array[0..501] of real;
 v:array[0..501] of boolean;
 n,m,i,j,ans:longint;

Procedure fopen;
  begin
  assign(input,'p3129.in');
  assign(output,'p3129.out');
  reset(input);
  rewrite(output);
end;

Procedure fclose;
  begin
  close(input);
  close(output);
end;

Function l(px,py,pz:real):real;inline;
  begin
  exit(sqrt(sqr(px)+sqr(py)+sqr(pz)));
end;

  begin

  while true do
    begin
    readln(n);
    if n=0 then break;
    for i:=1 to n do
      readln(x[i],y[i],z[i]);
    readln(m);
    for i:=1 to m do
      readln(x2[i],y2[i],z2[i],pi[i]);
    fillchar(v,sizeof(v),false);
    
    for i:=1 to n do
      for j:=1 to m do
        if (x[i]*x2[j]+y[i]*y2[j]+z[i]*z2[j])/l(x[i],y[i],z[i])/l(x2[j],y2[j],z2[j])-cos(pi[j])> -0.00000001 then
          begin
          v[i]:=true;
          break;
        end;
    ans:=0;
    for i:=1 to n do
      if v[i] then inc(ans);
    writeln(ans);
  end;

end.