Finding a plausible answer and proving that it follows every rule are different jobs.
01 / The problem
Turn the puzzle into constraints.
The July 2026 Jane Street puzzle combined schedule interpretation, three-dimensional knight moves, regional tower placement, and score arithmetic. A valid route had to satisfy all of them, including the no-repeat rule and the final stopping condition.
I treated it as an exact reconstruction problem. The search tests schedule interpretations against the arithmetic, then joins path segments between forced clue moves while enforcing the geometric and regional constraints.
- Schedule constant
- K = 7
- Path length
- 54 moves
- Check
- Separate verifier
Geometry. Check three-dimensional knight legality, regional tower placement, and the no-repeat rule.
Arithmetic. Recompute the scoring schedule, clue scores, and unvisited-neighbor sums.
Verification. Run a separate check of the proposed path rather than treating search completion as proof.
Recorded outputs from the solver package. This display does not execute the original solver.
02 / The work
Do not let the search grade itself.
A solver can produce a convincing-looking result while repeating an error in its own assumptions. I wrote a separate plain-Python verifier to recompute legality and scoring from the board, tower placements, schedule, and path coordinates.
The repository also generates a machine-readable solution, a path table, a clue audit, and unvisited-neighbor sums. Those outputs make the answer inspectable without asking a reader to trust a search log.
03 / The judgment
Leave a reproducible record.
The retained solution records K = 7, a 54-move path, and a final answer of 33,609. The implementation uses the Python standard library; the search, verification, and artifact-writing responsibilities are separate.
The useful result is the complete chain: a constraint model, an exact search, a second check, and outputs that explain what was checked. The solver record is distinct from Jane Street’s own publication of correct submissions.
04 / Decisions
What I chose.
And why.
- Exact reconstruction
- Forced clues and scoring arithmetic constrain the search instead of relying on a sequence of guesses.
- Independent verifier
- Recheck the proposed path outside the search procedure.
- Inspectable outputs
- The path table and clue audit expose the work behind the final number.
05 / Result
What came out of it.
A retained solver package recording K = 7, a 54-move path, the answer 33,609, and separate verification artifacts.
Status & source notes
The numerical result is drawn from the retained solver repository. The public dossier does not embed the original code or establish official leaderboard confirmation. No claim of a fresh execution or independent organizer verification is made by this page.
Case study updated September 12, 2026.