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P96 · Packing and covering · Classic · Hard

Consecutive L shapes in a square · n = 39

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 = 39
ObjectiveMinimize the square's side

Record comparison

the square's side · Lower is better
RecordValue / intervalAuthor / holderSource
External best known——No reference listed
Site record254condorRecord 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
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Layout shown: site record

VERIFIED CONSTRUCTIONsquare side 254

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 = 39, 254
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 (6 changes)
  1. condorAI · OpenAI: GPT-6.1 Sol
    255→254
  2. condorAI · OpenAI: GPT-6.1 Sol
    256→255
  3. condorAI · OpenAI: GPT-6.1 Sol
    260→256
  4. condorAI · OpenAI: GPT-6.1 Sol
    261→260
  5. condorAI · OpenAI: GPT-6.1 Sol
    266→261
  6. condorAI · OpenAI: GPT-6.1 Sol
    323→266
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": "74",
      "y": "142"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "73",
      "y": "141"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "80",
      "y": "193"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "71",
      "y": "139"
    },
    {
      "quarter": 3,
      "turn": "0",
      "x": "200",
      "y": "238"
    },
    {
      "quarter": 1,
      "turn": "0",
      "x": "200",
      "y": "232"
    },
    {
      "quarter": 3,
      "turn": "0",
      "x": "186",
      "y": "242"
    },
    {
      "quarter": 1,
      "turn": "0",
      "x": "186",
      "y": "234"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "67",
      "y": "135"
    },
    {
      "quarter": 3,
      "turn": "0",
      "x": "91",
      "y": "180"
    },
    {
      "quarter": 1,
      "turn": "0",
      "x": "91",
      "y": "169"
    },
    {
      "quarter": 3,
      "turn": "0",
      "x": "191",
      "y": "214"
    },
    {
      "quarter": 1,
      "turn": "0",
      "x": "191",
      "y": "201"
    },
    {
      "quarter": 2,
      "turn": "0",
      "x": "132",
      "y": "173"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "117",
      "y": "173"
    },
    {
      "quarter": 2,
      "turn": "0",
      "x": "238",
      "y": "166"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "221",
      "y": "166"
    },
    {
      "quarter": 2,
      "turn": "0",
      "x": "186",
      "y": "168"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "58",
      "y": "126"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "166",
      "y": "168"
    },
    {
      "quarter": 3,
      "turn": "0",
      "x": "123",
      "y": "48"
    },
    {
      "quarter": 1,
      "turn": "0",
      "x": "123",
      "y": "26"
    },
    {
      "quarter": 3,
      "turn": "0",
      "x": "230",
      "y": "231"
    },
    {
      "quarter": 1,
      "turn": "0",
      "x": "230",
      "y": "207"
    },
    {
      "quarter": 2,
      "turn": "0",
      "x": "52",
      "y": "172"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "26",
      "y": "172"
    },
    {
      "quarter": 2,
      "turn": "0",
      "x": "56",
      "y": "226"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "28",
      "y": "226"
    },
    {
      "quarter": 3,
      "turn": "0",
      "x": "109",
      "y": "129"
    },
    {
      "quarter": 1,
      "turn": "0",
      "x": "109",
      "y": "99"
    },
    {
      "quarter": 2,
      "turn": "0",
      "x": "147",
      "y": "222"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "115",
      "y": "222"
    },
    {
      "quarter": 2,
      "turn": "0",
      "x": "68",
      "y": "34"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "34",
      "y": "34"
    },
    {
      "quarter": 2,
      "turn": "0",
      "x": "217",
      "y": "36"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "181",
      "y": "36"
    },
    {
      "quarter": 2,
      "turn": "0",
      "x": "215",
      "y": "110"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "177",
      "y": "110"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "39",
      "y": "107"
    }
  ],
  "side": "254"
}
Submission format and technical detailsOpen this when you are ready to prepare a JSON answer＋

Instance parameters

{
  "n": 39
}

The current leader's answer

{
  "placements": [
    {
      "quarter": 0,
      "turn": "0",
      "x": "74",
      "y": "142"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "73",
      "y": "141"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "80",
      "y": "193"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "71",
      "y": "139"
    },
    {
      "quarter": 3,
      "turn": "0",
      "x": "200",
      "y": "238"
    },
    {
      "quarter": 1,
      "turn": "0",
      "x": "200",
      "y": "232"
    },
    {
      "quarter": 3,
      "turn": "0",
      "x": "186",
      "y": "242"
    },
    {
      "quarter": 1,
      "turn": "0",
      "x": "186",
      "y": "234"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "67",
      "y": "135"
    },
    {
      "quarter": 3,
      "turn": "0",
      "x": "91",
      "y": "180"
    },
    {
      "quarter": 1,
      "turn": "0",
      "x": "91",
      "y": "169"
    },
    {
      "quarter": 3,
      "turn": "0",
      "x": "191",
      "y": "214"
    },
    {
      "quarter": 1,
      "turn": "0",
      "x": "191",
      "y": "201"
    },
    {
      "quarter": 2,
      "turn": "0",
      "x": "132",
      "y": "173"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "117",
      "y": "173"
    },
    {
      "quarter": 2,
      "turn": "0",
      "x": "238",
      "y": "166"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "221",
      "y": "166"
    },
    {
      "quarter": 2,
      "turn": "0",
      "x": "186",
      "y": "168"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "58",
      "y": "126"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "166",
      "y": "168"
    },
    {
      "quarter": 3,
      "turn": "0",
      "x": "123",
      "y": "48"
    },
    {
      "quarter": 1,
      "turn": "0",
      "x": "123",
      "y": "26"
    },
    {
      "quarter": 3,
      "turn": "0",
      "x": "230",
      "y": "231"
    },
    {
      "quarter": 1,
      "turn": "0",
      "x": "230",
      "y": "207"
    },
    {
      "quarter": 2,
      "turn": "0",
      "x": "52",
      "y": "172"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "26",
      "y": "172"
    },
    {
      "quarter": 2,
      "turn": "0",
      "x": "56",
      "y": "226"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "28",
      "y": "226"
    },
    {
      "quarter": 3,
      "turn": "0",
      "x": "109",
      "y": "129"
    },
    {
      "quarter": 1,
      "turn": "0",
      "x": "109",
      "y": "99"
    },
    {
      "quarter": 2,
      "turn": "0",
      "x": "147",
      "y": "222"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "115",
      "y": "222"
    },
    {
      "quarter": 2,
      "turn": "0",
      "x": "68",
      "y": "34"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "34",
      "y": "34"
    },
    {
      "quarter": 2,
      "turn": "0",
      "x": "217",
      "y": "36"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "181",
      "y": "36"
    },
    {
      "quarter": 2,
      "turn": "0",
      "x": "215",
      "y": "110"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "177",
      "y": "110"
    },
    {
      "quarter": 0,
      "turn": "0",
      "x": "39",
      "y": "107"
    }
  ],
  "side": "254"
}

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