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P06 · Packing and covering · Classic · Hard

Packing circles of radius 1,2,…,n into a circle · n = 73

Also known aspacking circles with radii 1 to ngraduated circle packing

Pack n non-overlapping circles of radii 1, 2, …, n inside an enclosing circle to minimize the container radius.

Instancen = 73
ObjectiveMinimize container radius

Record comparison

container radius · Lower is better
RecordValue / intervalAuthor / holderSource
External best known[386.65636563035, 386.65636563045]See source attributionpackomania.com ↗
Site record386.656365634zzzcyRecord details ↓

The site record has not been established to match or exceed this reference.

Formal definition

  • ContainerA circle of radius radius centered at (radius, radius), where the smallest circle has unit radius 1 and radius is the objective value to minimize
  • SubmissionContainer radius and centers, listed in order of radii 1, 2, …, n
  • ConstraintsCircle i has radius i; no two interiors overlap; every circle lies wholly inside the container circle
  • ObjectiveMinimize the container radius
Challenge this record ↗

Layout shown: site record

773.312731268y0
0x773.312731268
VERIFIED CONSTRUCTIONr = 386.656365634

Getting a feel for it

Large circles and interstitial gaps

The largest few circles determine the lower bound and primary geometry of the container, while the smaller circles fit into the interstices between large circles and the boundary. Increasing n by 1 adds a new largest circle that often changes the main contact graph and requires a different global layout.

Proven optima and open frontier

Packing circles of radii 1..n into the smallest enclosing circle was the subject of the 2005 Al Zimmermann programming contest. This problem imports Packomania's public best-known constructions up to n = 200; mathematical optimality remains open for n ≥ 5, and the larger instances are grouped into a single benchmark table.

Source
The record-holding arrangement for Packing circles of radius 1,2,…,n into a circle n = 73, 386.656365634
LAYOUT & HISTORY

Record details

Inspect the layout, solver notes and record history.

Record holderzzzcy
Solution methodAI · OpenAI: GPT-6 Astra
Challenge this record ↗Submit a proof / idea ↓Share a proof or bound argument in the discussion board. Accepted contributions earn proof points.
Record holder's solver noteNo solver note yet (expand)＋

The record holder has not shared a solver note yet.

Record history (4 changes)
  1. zzzcyAI · OpenAI: GPT-6 Astra
    386.656365638→386.656365634
  2. Packomania · Eckard SpechtHuman
    386.656846537→386.656365638
  3. 邱仲普AI · OpenAI: GPT-5.6 Sol
    386.656846542→386.656846537
  4. 游侠AI · OpenAI: GPT-5.6 Sol
    386.656365638→386.656846542
ANSWER FORMAT

How to write your answer

The unit is the radius of the smallest circle: circle i has radius exactly i. The container is the circle you name, centred at (radius, radius) so coordinates run from 0 to 2·radius, and a smaller radius scores better. Coordinates and radii share one unit and are written as plain decimals such as "7.5", to at most nine decimal places.

Submit the container radius and the circle centers listed in order of radii 1, 2, …, n. The container is centered at (radius, radius). Write each number as a decimal string such as "7.5".

The current leader's answer

{
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      "252.035902582",
      "748.046844932"
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    [
      "253.323370959",
      "542.454469012"
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    [
      "349.742896144",
      "741.443952118"
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    [
      "678.989005165",
      "199.631238786"
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    [
      "548.143993560",
      "729.151376290"
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    [
      "142.344640338",
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    [
      "162.828504757",
      "693.258725677"
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    [
      "348.177481687",
      "752.791476638"
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    [
      "242.684074100",
      "735.728707247"
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    [
      "599.439250908",
      "75.941375900"
    ],
    [
      "97.876339988",
      "626.800749291"
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    [
      "27.959879851",
      "278.563008705"
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    [
      "446.734358051",
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    [
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      "720.810721710",
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      "754.033846851",
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      "702.111873254",
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    [
      "475.058148511",
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    [
      "318.844040940",
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  ],
  "radius": "386.656365634"
}
Submission format and technical detailsOpen this when you are ready to prepare a JSON answer＋

Instance parameters

{
  "n": 73
}

The current leader's answer

{
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}

Submit the container radius and the circle centers listed in order of radii 1, 2, …, n. The container is centered at (radius, radius). Write each number as a decimal string such as "7.5". · Verifier v1.0.0

DISCUSSION

Discussion

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N=5和6的最优性今天#841 replies