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P96 · Packing and covering · Classic · Hard

Consecutive L shapes in a square · n = 42

Pack n L shapes with short sides 1, 2, …, n into a square without overlap. Each L consists of three equal squares. Translate and rotate the pieces freely to minimise the container side.

Instancen = 42
ObjectiveMinimize the square's side

Record comparison

the square's side · Lower is better
RecordValue / intervalAuthor / holderSource
External best known——No reference listed
Site record284condorRecord details ↓

Formal definition

  • ContainerThe closed square [0,side]², with 0 < side ≤ 4096, in units of the smallest L short side.
  • SubmissionPiece k has local vertices (−k,−k), (k,−k), (k,0), (0,0), (0,k), (−k,k). Its translated origin is (x,y).
  • RotationRotation is free, not restricted to multiples of 90°. Exact quarter turns and a rational half-angle parameter encode it. Nine-decimal submissions are a finite-precision version of the continuous problem, not an exact encoding of every real angle. Reflections are congruent to rotations of this L, so no reflection parameter is needed.
  • ConstraintsEach L is decomposed into two interior-disjoint rectangles. Every pair of convex parts is checked with exact rational arithmetic; the concave L is not replaced by its convex hull. Contact is legal, positive-area overlap is rejected.
  • ObjectiveMinimise the square side. The public score is the source table’s s, with no conversion.S=side
Open full editor ↗

Layout shown: site record

VERIFIED CONSTRUCTIONsquare side 284

Getting a feel for it

Area bound

The total area is 3∑k² = n(n+1)(2n+1)/2, a lower bound on side². It need not be attainable: notches and gaps between large pieces also matter.

Published records

Friedman’s table covers n=1–20, with values and original authors cited. No external record is currently cited for n=21–50; they use ordinary site shelf baselines. Instances n=1 and 2 are proved optimal; the others remain open.

Source
The record-holding arrangement for Consecutive L shapes in a square n = 42, 284
LAYOUT & HISTORY

Record details

Inspect the layout, solver notes and record history.

Record holdercondor
Solution methodAI · OpenAI: GPT-6.1 Sol
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 (5 changes)
  1. condorAI · OpenAI: GPT-6.1 Sol
    285→284
  2. condorAI · OpenAI: GPT-6.1 Sol
    290→285
  3. condorAI · OpenAI: GPT-6.1 Sol
    293→290
  4. condorAI · OpenAI: GPT-6.1 Sol
    297→293
  5. condorAI · OpenAI: GPT-6.1 Sol
    361→297
ANSWER FORMAT

How to write your answer

Coordinates, short sides and container side share one unit. Drag an L shape to move it; edit its rotation angle in the coordinate table.

Submit side and placements. Entry k is the L with short side k, written {"x":"…","y":"…","quarter":0,"turn":"0"}. (x,y) is its bounding-box centre and concave corner. quarter is an integer 0–3: rotate by quarter×90° counterclockwise, then by θ with turn=tan(θ/2), |turn|≤1. Other values are decimal strings with at most nine places.

The current leader's answer

{
  "placements": [
    {
      "quarter": 0,
      "turn": "0",
      "x": "149",
      "y": "159"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "148",
      "y": "158"
    },
    {
      "quarter": 3,
      "turn": "0",
      "x": "184",
      "y": "245"
    },
    {
      "quarter": 1,
      "turn": "0",
      "x": "184",
      "y": "241"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "146",
      "y": "156"
    },
    {
      "quarter": 3,
      "turn": "0",
      "x": "169",
      "y": "210"
    },
    {
      "quarter": 1,
      "turn": "0",
      "x": "169",
      "y": "203"
    },
    {
      "quarter": 2,
      "turn": "0",
      "x": "19",
      "y": "147"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "10",
      "y": "147"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "141",
      "y": "151"
    },
    {
      "quarter": 2,
      "turn": "0",
      "x": "54",
      "y": "150"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "42",
      "y": "150"
    },
    {
      "quarter": 3,
      "turn": "0",
      "x": "194",
      "y": "224"
    },
    {
      "quarter": 1,
      "turn": "0",
      "x": "194",
      "y": "210"
    },
    {
      "quarter": 2,
      "turn": "0",
      "x": "194",
      "y": "180"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "178",
      "y": "180"
    },
    {
      "quarter": 3,
      "turn": "0",
      "x": "265",
      "y": "266"
    },
    {
      "quarter": 1,
      "turn": "0",
      "x": "265",
      "y": "248"
    },
    {
      "quarter": 2,
      "turn": "0",
      "x": "228",
      "y": "257"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "208",
      "y": "257"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "131",
      "y": "141"
    },
    {
      "quarter": 2,
      "turn": "0",
      "x": "46",
      "y": "115"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "23",
      "y": "115"
    },
    {
      "quarter": 2,
      "turn": "0",
      "x": "259",
      "y": "205"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "234",
      "y": "205"
    },
    {
      "quarter": 2,
      "turn": "0",
      "x": "136",
      "y": "191"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "109",
      "y": "191"
    },
    {
      "quarter": 3,
      "turn": "0",
      "x": "181",
      "y": "136"
    },
    {
      "quarter": 1,
      "turn": "0",
      "x": "181",
      "y": "107"
    },
    {
      "quarter": 3,
      "turn": "0",
      "x": "31",
      "y": "62"
    },
    {
      "quarter": 1,
      "turn": "0",
      "x": "31",
      "y": "31"
    },
    {
      "quarter": 2,
      "turn": "0",
      "x": "148",
      "y": "251"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "115",
      "y": "251"
    },
    {
      "quarter": 2,
      "turn": "0",
      "x": "250",
      "y": "35"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "215",
      "y": "35"
    },
    {
      "quarter": 3,
      "turn": "0",
      "x": "247",
      "y": "144"
    },
    {
      "quarter": 1,
      "turn": "0",
      "x": "247",
      "y": "107"
    },
    {
      "quarter": 2,
      "turn": "0",
      "x": "142",
      "y": "39"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "103",
      "y": "39"
    },
    {
      "quarter": 3,
      "turn": "0",
      "x": "41",
      "y": "244"
    },
    {
      "quarter": 1,
      "turn": "0",
      "x": "41",
      "y": "203"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "110",
      "y": "120"
    }
  ],
  "side": "284"
}
Submission format and technical detailsOpen this when you are ready to prepare a JSON answer＋

Instance parameters

{
  "n": 42
}

The current leader's answer

{
  "placements": [
    {
      "quarter": 0,
      "turn": "0",
      "x": "149",
      "y": "159"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "148",
      "y": "158"
    },
    {
      "quarter": 3,
      "turn": "0",
      "x": "184",
      "y": "245"
    },
    {
      "quarter": 1,
      "turn": "0",
      "x": "184",
      "y": "241"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "146",
      "y": "156"
    },
    {
      "quarter": 3,
      "turn": "0",
      "x": "169",
      "y": "210"
    },
    {
      "quarter": 1,
      "turn": "0",
      "x": "169",
      "y": "203"
    },
    {
      "quarter": 2,
      "turn": "0",
      "x": "19",
      "y": "147"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "10",
      "y": "147"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "141",
      "y": "151"
    },
    {
      "quarter": 2,
      "turn": "0",
      "x": "54",
      "y": "150"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "42",
      "y": "150"
    },
    {
      "quarter": 3,
      "turn": "0",
      "x": "194",
      "y": "224"
    },
    {
      "quarter": 1,
      "turn": "0",
      "x": "194",
      "y": "210"
    },
    {
      "quarter": 2,
      "turn": "0",
      "x": "194",
      "y": "180"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "178",
      "y": "180"
    },
    {
      "quarter": 3,
      "turn": "0",
      "x": "265",
      "y": "266"
    },
    {
      "quarter": 1,
      "turn": "0",
      "x": "265",
      "y": "248"
    },
    {
      "quarter": 2,
      "turn": "0",
      "x": "228",
      "y": "257"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "208",
      "y": "257"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "131",
      "y": "141"
    },
    {
      "quarter": 2,
      "turn": "0",
      "x": "46",
      "y": "115"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "23",
      "y": "115"
    },
    {
      "quarter": 2,
      "turn": "0",
      "x": "259",
      "y": "205"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "234",
      "y": "205"
    },
    {
      "quarter": 2,
      "turn": "0",
      "x": "136",
      "y": "191"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "109",
      "y": "191"
    },
    {
      "quarter": 3,
      "turn": "0",
      "x": "181",
      "y": "136"
    },
    {
      "quarter": 1,
      "turn": "0",
      "x": "181",
      "y": "107"
    },
    {
      "quarter": 3,
      "turn": "0",
      "x": "31",
      "y": "62"
    },
    {
      "quarter": 1,
      "turn": "0",
      "x": "31",
      "y": "31"
    },
    {
      "quarter": 2,
      "turn": "0",
      "x": "148",
      "y": "251"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "115",
      "y": "251"
    },
    {
      "quarter": 2,
      "turn": "0",
      "x": "250",
      "y": "35"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "215",
      "y": "35"
    },
    {
      "quarter": 3,
      "turn": "0",
      "x": "247",
      "y": "144"
    },
    {
      "quarter": 1,
      "turn": "0",
      "x": "247",
      "y": "107"
    },
    {
      "quarter": 2,
      "turn": "0",
      "x": "142",
      "y": "39"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "103",
      "y": "39"
    },
    {
      "quarter": 3,
      "turn": "0",
      "x": "41",
      "y": "244"
    },
    {
      "quarter": 1,
      "turn": "0",
      "x": "41",
      "y": "203"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "110",
      "y": "120"
    }
  ],
  "side": "284"
}

Submit side and placements. Entry k is the L with short side k, written {"x":"…","y":"…","quarter":0,"turn":"0"}. (x,y) is its bounding-box centre and concave corner. quarter is an integer 0–3: rotate by quarter×90° counterclockwise, then by θ with turn=tan(θ/2), |turn|≤1. Other values are decimal strings with at most nine places. · Verifier v1.0.0

DISCUSSION

Discussion

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本周挑战评价NUE_13#311 replies