circles = [
  [ 1.6417233788,  1.6121789534, 0.0848270516],
  [-1.4944608174,  1.2077959613, 1.1039549836],
  [ 0.6110294452, -0.6907087527, 0.9089162485],
  [ 0.3844862411,  0.2923344616, 0.2375743054],
  [-0.2495892950, -0.3832854473, 1.0845181219],
  [ 1.7813504266,  1.6178237031, 0.8162655711],
  [-0.1985249206, -0.8343333301, 0.0538864941],
  [-1.7011985145, -0.1263820964, 0.4776976918],
  [-0.4319462812,  1.4104420482, 0.7886291537],
  [ 0.2178372997, -0.9499557344, 0.0357871187],
  [-0.6294854565, -1.3078893852, 0.7653357688],
  [ 1.7952608455,  0.6281269104, 0.2727652452],
  [ 1.4168575317,  1.0683357171, 1.1016025378],
  [ 1.4637371396,  0.9463877418, 1.1846214562],
  [-0.5263668798,  1.7315156631, 1.4428514068],
  [-1.2197352481,  0.9144146579, 1.0727263474],
  [-0.1389358881,  0.1092805780, 0.7350208828],
  [ 1.5293954595,  0.0030278255, 1.2472867347],
  [-0.5258728625,  1.3782633069, 1.3495508831],
  [-0.1403562064,  0.2437382535, 1.3804956588],
  [ 0.8055826339, -0.0482092025, 0.3327165165],
  [-0.6311979224,  0.7184578971, 0.2491045282],
  [ 1.4685857879, -0.8347049536, 1.3670667538],
  [-0.6855727502,  1.6465021616, 1.0593087096],
  [ 0.0152957411,  0.0638919221, 0.9771215985],
]

def minmax_circle(circles)
  xmin = circles.map {|xc, yc, radius| xc - radius}.min
  xmax = circles.map {|xc, yc, radius| xc + radius}.max
  ymin = circles.map {|xc, yc, radius| yc - radius}.min
  ymax = circles.map {|xc, yc, radius| yc + radius}.max
  [xmin, xmax, ymin, ymax]
end

# remove internal circle
def select_circle(circles)
  circles = circles.sort_by{|cx,cy,r| -r}
  size = circles.size
  select = [*0...size]
  for i in 0...size-1
    xi,yi,ri = circles[i].to_a
    for j in i+1...size
      xj,yj,rj = circles[j].to_a
      select -= [j]  if (xi-xj)**2 + (yi-yj)**2 <= (ri-rj)**2
    end
  end
  circles.values_at(*select)
end
circles = select_circle(circles)