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Comment by mbostock | Hacker News Reader

You can solve by finding the point <x, y> that minimizes the distance from any point in any input circle: \sqrt{(x_p - x) ^ 2 + (y_p - y) ^ 2} + r_p for p ∈ L. This is the center of the smallest enclosing circle. Once you have the center, you can iterate over every input circle to compute its radius.

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That's clever! I updated the code and it seems to work for the several times I refreshed now. Thanks!

This was the final cost function that worked:

  let encloseCost = 0;  
  let farthestPointCost = 0;  
  for (let i = 0; i < B.length; i++) {
    const b = B[i];
    const dx = b.x - a.x;
    const dy = b.y - a.y;
    encloseCost += Math.max(
      0,
      -a.r + (b.r + Math.sqrt(dx * dx + dy * dy))
    );
    farthestPointCost = Math.max(
      farthestPointCost,
      b.r + Math.sqrt(dx * dx + dy * dy)
    );
  }
  const radiusCost = Math.abs(a.r);
  
  const totalCost = encloseCost + farthestPointCost + radiusCost;

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