The Two Paths
(Published on 13. February 2026, 13:39 by balpha)
Normal Sudoku rules apply. Boxes and columns are numbered in the usual way (by English reading order).
Draw two paths along the grid, defined by waypoints. Two waypoints are connected by a straight line that may be horizontal, vertical, or diagonal. A path never intersects with itself.
On path A, the waypoints are, in order, the 1 in column 1, the 2 in column 2, the 3 in column 3, and so on until the 9 in column 9.
On path B, the waypoints are, in order, the 1 in box 1, the 2 in box 2, the 3 in box 3, and so on until the 9 in box 9. On path B, no two waypoints are adjacent on the path, and a digit on the path between two waypoints is either the same digit as one of those two waypoints, or it divides the sum of those two waypoints.
Path B splits the grid into exactly two orthogonally connected regions (i.e. you can color digits on the path in yellow, and all other digits in green or blue, such that all the green digits form one orthogonally connected region, all the blue digits do the same, and no pair of a green and a blue digit is ever orthogonally connected).
In one of those regions, a digit always has a difference of at least 3 with any orthogonally adjacent digit on path B.
In the other region, no 4 ever sits orthogonally adjacent to a digit on path B.
Solution code: Row 2, left to right
