P87 · Packing and covering · Classic · Easy

Equal discs covering a disc · n = 37

Cover the largest possible disc with n unit-radius discs. Maximise the covered disc radius.

Instancen = 37
ObjectiveMaximize covered disc radius

Record comparison

covered disc radius · Higher is better
RecordValue / intervalAuthor / holderSource
External best known——No reference listed
Site recordNo player record yet——

Formal definition

  • ContainerThe editor and certificate normalize to the closed unit disc centred at (1,1). This is a coordinate convention only; scores use the literature's unit-piece scale. Boundary contact is allowed.
  • SubmissionSubmit {radius, placements:[{x,y,turn},…]}, with decimal strings of at most nine places. x,y are centres; circles require turn=0, polygons use turn=tan(θ/2). Coordinates and turn lie in ±4; 0 < radius ≤ 4.
  • ConstraintsThe n distinct centres lie in the target disc. Covering discs may overlap and protrude, but must cover every target point.
  • PrecisionInput decimals are exact rationals; regular-polygon vertices are algebraic, not rounded templates. Feasibility has no floating-point tolerance. A finite-decimal certificate is not a continuous optimality proof.
  • ObjectiveCovered disc radius R = 1/r, larger is better.
Open the full editor ↗

Layout shown: starter layout

VERIFIED CONSTRUCTIONVERIFIED CONSTRUCTION

Getting a feel for it

Source and certificate

External targets are converted with their printed precision; decimal coordinate certificates are separate. Reconstruction loss never lowers the literature target, and a source construction is not automatically an optimality proof.

Source
The current arrangement for Equal discs covering a disc n = 37
LAYOUT & HISTORY

Starter layout

Inspect the layout, solver notes and record history.

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ANSWER FORMAT

How to write your answer

the closed unit disc centred at (1,1)

Submit {radius, placements:[{x,y,turn},…]}, with decimal strings of at most nine places. x,y are centres; circles require turn=0, polygons use turn=tan(θ/2). Coordinates and turn lie in ±4; 0 < radius ≤ 4.

Starter answer

{
  "placements": [
    {
      "turn": "0",
      "x": "1.000065636",
      "y": "1.000002522"
    },
    {
      "turn": "0",
      "x": "0.826733391",
      "y": "1.286759184"
    },
    {
      "turn": "0",
      "x": "0.664792593",
      "y": "0.991724683"
    },
    {
      "turn": "0",
      "x": "1.161856567",
      "y": "1.294758726"
    },
    {
      "turn": "0",
      "x": "0.838359624",
      "y": "0.705088396"
    },
    {
      "turn": "0",
      "x": "1.335354085",
      "y": "1.007731737"
    },
    {
      "turn": "0",
      "x": "1.173767036",
      "y": "0.713368747"
    },
    {
      "turn": "0",
      "x": "0.491807250",
      "y": "1.279113156"
    },
    {
      "turn": "0",
      "x": "0.985558579",
      "y": "1.581713343"
    },
    {
      "turn": "0",
      "x": "0.501605467",
      "y": "0.699042505"
    },
    {
      "turn": "0",
      "x": "1.497246975",
      "y": "1.302320708"
    },
    {
      "turn": "0",
      "x": "0.650633734",
      "y": "1.574069669"
    },
    {
      "turn": "0",
      "x": "1.012662570",
      "y": "0.418466794"
    },
    {
      "turn": "0",
      "x": "0.328537141",
      "y": "0.986280384"
    },
    {
      "turn": "0",
      "x": "1.509306676",
      "y": "0.720744750"
    },
    {
      "turn": "0",
      "x": "1.320954897",
      "y": "1.589265717"
    },
    {
      "turn": "0",
      "x": "0.676282252",
      "y": "0.412429336"
    },
    {
      "turn": "0",
      "x": "1.670704577",
      "y": "1.015221283"
    },
    {
      "turn": "0",
      "x": "1.348041433",
      "y": "0.426695103"
    },
    {
      "turn": "0",
      "x": "0.305576060",
      "y": "1.545078008"
    },
    {
      "turn": "0",
      "x": "0.166690169",
      "y": "1.291497700"
    },
    {
      "turn": "0",
      "x": "0.836693975",
      "y": "1.868010508"
    },
    {
      "turn": "0",
      "x": "0.181143388",
      "y": "0.670648199"
    },
    {
      "turn": "0",
      "x": "1.126991151",
      "y": "1.874824699"
    },
    {
      "turn": "0",
      "x": "0.330898453",
      "y": "0.422634436"
    },
    {
      "turn": "0",
      "x": "1.668730019",
      "y": "1.572919392"
    },
    {
      "turn": "0",
      "x": "0.876608943",
      "y": "0.127831197"
    },
    {
      "turn": "0",
      "x": "1.819861520",
      "y": "1.328229970"
    },
    {
      "turn": "0",
      "x": "1.164076050",
      "y": "0.132647672"
    },
    {
      "turn": "0",
      "x": "1.831920874",
      "y": "0.707912277"
    },
    {
      "turn": "0",
      "x": "1.693969700",
      "y": "0.455446082"
    },
    {
      "turn": "0",
      "x": "0.491167256",
      "y": "1.837840660"
    },
    {
      "turn": "0",
      "x": "0.020419626",
      "y": "0.977446529"
    },
    {
      "turn": "0",
      "x": "1.473984126",
      "y": "1.858369522"
    },
    {
      "turn": "0",
      "x": "0.531122988",
      "y": "0.138972302"
    },
    {
      "turn": "0",
      "x": "1.980323032",
      "y": "1.020636187"
    },
    {
      "turn": "0",
      "x": "1.509500606",
      "y": "0.162268021"
    }
  ],
  "radius": "0.193821332"
}
Submission format and technical detailsOpen this when you are ready to prepare a JSON answer+

Instance parameters

{
  "n": 37,
  "sides": 5
}

Starter answer

{
  "placements": [
    {
      "turn": "0",
      "x": "1.000065636",
      "y": "1.000002522"
    },
    {
      "turn": "0",
      "x": "0.826733391",
      "y": "1.286759184"
    },
    {
      "turn": "0",
      "x": "0.664792593",
      "y": "0.991724683"
    },
    {
      "turn": "0",
      "x": "1.161856567",
      "y": "1.294758726"
    },
    {
      "turn": "0",
      "x": "0.838359624",
      "y": "0.705088396"
    },
    {
      "turn": "0",
      "x": "1.335354085",
      "y": "1.007731737"
    },
    {
      "turn": "0",
      "x": "1.173767036",
      "y": "0.713368747"
    },
    {
      "turn": "0",
      "x": "0.491807250",
      "y": "1.279113156"
    },
    {
      "turn": "0",
      "x": "0.985558579",
      "y": "1.581713343"
    },
    {
      "turn": "0",
      "x": "0.501605467",
      "y": "0.699042505"
    },
    {
      "turn": "0",
      "x": "1.497246975",
      "y": "1.302320708"
    },
    {
      "turn": "0",
      "x": "0.650633734",
      "y": "1.574069669"
    },
    {
      "turn": "0",
      "x": "1.012662570",
      "y": "0.418466794"
    },
    {
      "turn": "0",
      "x": "0.328537141",
      "y": "0.986280384"
    },
    {
      "turn": "0",
      "x": "1.509306676",
      "y": "0.720744750"
    },
    {
      "turn": "0",
      "x": "1.320954897",
      "y": "1.589265717"
    },
    {
      "turn": "0",
      "x": "0.676282252",
      "y": "0.412429336"
    },
    {
      "turn": "0",
      "x": "1.670704577",
      "y": "1.015221283"
    },
    {
      "turn": "0",
      "x": "1.348041433",
      "y": "0.426695103"
    },
    {
      "turn": "0",
      "x": "0.305576060",
      "y": "1.545078008"
    },
    {
      "turn": "0",
      "x": "0.166690169",
      "y": "1.291497700"
    },
    {
      "turn": "0",
      "x": "0.836693975",
      "y": "1.868010508"
    },
    {
      "turn": "0",
      "x": "0.181143388",
      "y": "0.670648199"
    },
    {
      "turn": "0",
      "x": "1.126991151",
      "y": "1.874824699"
    },
    {
      "turn": "0",
      "x": "0.330898453",
      "y": "0.422634436"
    },
    {
      "turn": "0",
      "x": "1.668730019",
      "y": "1.572919392"
    },
    {
      "turn": "0",
      "x": "0.876608943",
      "y": "0.127831197"
    },
    {
      "turn": "0",
      "x": "1.819861520",
      "y": "1.328229970"
    },
    {
      "turn": "0",
      "x": "1.164076050",
      "y": "0.132647672"
    },
    {
      "turn": "0",
      "x": "1.831920874",
      "y": "0.707912277"
    },
    {
      "turn": "0",
      "x": "1.693969700",
      "y": "0.455446082"
    },
    {
      "turn": "0",
      "x": "0.491167256",
      "y": "1.837840660"
    },
    {
      "turn": "0",
      "x": "0.020419626",
      "y": "0.977446529"
    },
    {
      "turn": "0",
      "x": "1.473984126",
      "y": "1.858369522"
    },
    {
      "turn": "0",
      "x": "0.531122988",
      "y": "0.138972302"
    },
    {
      "turn": "0",
      "x": "1.980323032",
      "y": "1.020636187"
    },
    {
      "turn": "0",
      "x": "1.509500606",
      "y": "0.162268021"
    }
  ],
  "radius": "0.193821332"
}

Submit {radius, placements:[{x,y,turn},…]}, with decimal strings of at most nine places. x,y are centres; circles require turn=0, polygons use turn=tan(θ/2). Coordinates and turn lie in ±4; 0 < radius ≤ 4. · Verifier v1.0.0

DISCUSSION

Discussion

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