The Basilisk
(Published on 8. November 2025, 08:00 by Jreg)
Standard Sudoku rules: place the digits 1-9 once in every row, column and 3×3 box.
Draw a serpent in the grid. The serpent is a single unbranching line starting in one of the 3×3 boxes and passing through each box exactly once before stopping in the final box; the exact order in which the serpent visits these boxes is to be determined by the solver. The serpent only moves orthogonally (left, right, up, down) and cannot visit a single cell multiple times.
The boxes are numbered in a standard reading order. In each box number N, the serpent occupies exactly N cells. Those cells contain a consecutive set of digits 1 through N in any order. E.g.: In the middle row of boxes, the leftmost box is number 4. The serpent occupies 4 cells in this box and they contain the digits 1-4.
Cells separated by a white dot contain consecutive digits; the serpent cannot pass through any white dots. Cells that are a chess knight's move apart cannot contain the same digit unless both of them are inside the serpent.
Click HERE to solve in SudokuPad (with the correct solution uploaded)
Solution code: Digits in row 9 (from left to right)
Comments
on 12. November 2025, 03:41 by FibonacciCascade
Kept stumbling because I kept forgetting the anti-knight didn't apply to pairs of numbers on the serpent! lol Also I found a slightly different path to the serpent which was wrong. I thought I had deduced it down to one of two paths, but there was another possible path I overlooked, but funny enough, I was able to get pretty far with this incorrect path, and only had to untangle two boxes once I realized the mistake)
on 8. November 2025, 17:07 by TripleABattery
Very nice puzzle! Since I more or less solved this earlier (and did some exploration into setting something similar in the meantime) I was able to fly through a lot of the steps, but even so, I had a lot of fun, thanks :)
