P85 · Packing and covering · Classic · Hard

Squares in an equilateral triangle · n = 20

Pack n unit squares into an equilateral triangle container with boundary contact allowed and disjoint interiors, minimising the side length of the container triangle.

Instancen = 20
ObjectiveMinimize container triangle side

Record comparison

container triangle side · Lower is better
RecordValue / intervalAuthor / holderSource
External best known[7.61695, 7.61696)Haowei LinErich Friedman ↗
Site recordNo player record yet——

Formal definition

  • ContainerThe editor and certificate normalise the container to the equilateral triangle with vertices (0,0), (1,0), and (1/2,√3/2), while public scores are reported in the literature's unit-piece scale. Boundary contact is allowed.
  • SubmissionSubmit {radius, placements:[{x,y,turn},…]}, with each value written as a decimal string of at most nine places. Here x, y are centre coordinates; circles require turn = 0 and polygons use turn = tan(θ/2). Coordinates and turn must lie in [−4, 4], with 0 < radius ≤ 4.
  • ConstraintsExactly n congruent pieces lie wholly inside the container with pairwise disjoint interiors. Polygons may rotate independently by arbitrary angles.
  • PrecisionInput decimals are parsed as exact rationals and regular-polygon vertices are defined algebraically, with zero floating-point tolerance in feasibility checks.
  • ObjectiveContainer triangle side = 1/(2 sin(π/4) r), where smaller is better. Pages, leaderboards, and literature records share this unit with automatic conversion.
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Layout shown: starter layout

VERIFIED CONSTRUCTIONVERIFIED CONSTRUCTION

Getting a feel for it

Literature targets and coordinate certificates

Literature targets are converted at their published precision, while nine-decimal coordinate certificates are stored and displayed alongside the source values.

Source
The current arrangement for Squares in an equilateral triangle n = 20
LAYOUT & HISTORY

Starter layout

Inspect the layout, solver notes and record history.

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ANSWER FORMAT

How to write your answer

the equilateral triangle with vertices (0,0), (1,0), (1/2,√3/2)

Submit {radius, placements:[{x,y,turn},…]}, with each value written as a decimal string of at most nine places. Here x, y are centre coordinates; circles require turn = 0 and polygons use turn = tan(θ/2). Coordinates and turn must lie in [−4, 4], with 0 < radius ≤ 4.

Starter answer

{
  "placements": [
    {
      "turn": "0.131652498",
      "x": "0.486123621",
      "y": "0.710704738"
    },
    {
      "turn": "0.131652498",
      "x": "0.420470681",
      "y": "0.596990509"
    },
    {
      "turn": "0.131652498",
      "x": "0.561926044",
      "y": "0.579426240"
    },
    {
      "turn": "0.131652498",
      "x": "0.354825969",
      "y": "0.483290533"
    },
    {
      "turn": "0.131652498",
      "x": "0.496283007",
      "y": "0.465729166"
    },
    {
      "turn": "-0.122541828",
      "x": "0.662727702",
      "y": "0.441408945"
    },
    {
      "turn": "-0.068598303",
      "x": "0.571706786",
      "y": "0.332644473"
    },
    {
      "turn": "-0.131652498",
      "x": "0.734036221",
      "y": "0.329376706"
    },
    {
      "turn": "-0.395459928",
      "x": "0.414609275",
      "y": "0.328467898"
    },
    {
      "turn": "0.131652498",
      "x": "0.258855152",
      "y": "0.317064203"
    },
    {
      "turn": "-0.068598303",
      "x": "0.637864501",
      "y": "0.218055949"
    },
    {
      "turn": "-0.131652498",
      "x": "0.799999854",
      "y": "0.215124342"
    },
    {
      "turn": "0.131652498",
      "x": "0.193212116",
      "y": "0.203367129"
    },
    {
      "turn": "-0.414105290",
      "x": "0.476337674",
      "y": "0.197004097"
    },
    {
      "turn": "0.131652498",
      "x": "0.127569080",
      "y": "0.089670055"
    },
    {
      "turn": "-0.203095735",
      "x": "0.710810947",
      "y": "0.086310777"
    },
    {
      "turn": "-0.304463964",
      "x": "0.859248093",
      "y": "0.077102556"
    },
    {
      "turn": "0.414213562",
      "x": "0.424323257",
      "y": "0.065697223"
    },
    {
      "turn": "0.414213562",
      "x": "0.293037184",
      "y": "0.065643036"
    },
    {
      "turn": "-0.414213562",
      "x": "0.555609329",
      "y": "0.065643036"
    }
  ],
  "radius": "0.092833271"
}
Submission format and technical detailsOpen this when you are ready to prepare a JSON answer+

Instance parameters

{
  "n": 20,
  "sides": 5
}

Starter answer

{
  "placements": [
    {
      "turn": "0.131652498",
      "x": "0.486123621",
      "y": "0.710704738"
    },
    {
      "turn": "0.131652498",
      "x": "0.420470681",
      "y": "0.596990509"
    },
    {
      "turn": "0.131652498",
      "x": "0.561926044",
      "y": "0.579426240"
    },
    {
      "turn": "0.131652498",
      "x": "0.354825969",
      "y": "0.483290533"
    },
    {
      "turn": "0.131652498",
      "x": "0.496283007",
      "y": "0.465729166"
    },
    {
      "turn": "-0.122541828",
      "x": "0.662727702",
      "y": "0.441408945"
    },
    {
      "turn": "-0.068598303",
      "x": "0.571706786",
      "y": "0.332644473"
    },
    {
      "turn": "-0.131652498",
      "x": "0.734036221",
      "y": "0.329376706"
    },
    {
      "turn": "-0.395459928",
      "x": "0.414609275",
      "y": "0.328467898"
    },
    {
      "turn": "0.131652498",
      "x": "0.258855152",
      "y": "0.317064203"
    },
    {
      "turn": "-0.068598303",
      "x": "0.637864501",
      "y": "0.218055949"
    },
    {
      "turn": "-0.131652498",
      "x": "0.799999854",
      "y": "0.215124342"
    },
    {
      "turn": "0.131652498",
      "x": "0.193212116",
      "y": "0.203367129"
    },
    {
      "turn": "-0.414105290",
      "x": "0.476337674",
      "y": "0.197004097"
    },
    {
      "turn": "0.131652498",
      "x": "0.127569080",
      "y": "0.089670055"
    },
    {
      "turn": "-0.203095735",
      "x": "0.710810947",
      "y": "0.086310777"
    },
    {
      "turn": "-0.304463964",
      "x": "0.859248093",
      "y": "0.077102556"
    },
    {
      "turn": "0.414213562",
      "x": "0.424323257",
      "y": "0.065697223"
    },
    {
      "turn": "0.414213562",
      "x": "0.293037184",
      "y": "0.065643036"
    },
    {
      "turn": "-0.414213562",
      "x": "0.555609329",
      "y": "0.065643036"
    }
  ],
  "radius": "0.092833271"
}

Submit {radius, placements:[{x,y,turn},…]}, with each value written as a decimal string of at most nine places. Here x, y are centre coordinates; circles require turn = 0 and polygons use turn = tan(θ/2). Coordinates and turn must lie in [−4, 4], with 0 < radius ≤ 4. · Verifier v1.0.0

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