Inspired by the original T. Snyder’s “What If” article, I tried my hand at constructing a Sudoku problem whose difficulty increased as much as possible when a single element is removed, while retaining human solvability. This resulted in this pair of puzzles, one of which can be used as an introduction to Sudoku, while its near twin requires considerable experience to complete in a logical manner. Scanraid’s grader assigns them ratings of Gentle(27) and Tough (151), which concurs with my gut.
The puzzle below is the difficult one, while the easy version, and some spoilery commentary follows after the break.
Factor Lines Sudoku by Philip Newman
-
(This post is part of the Genuinely Approachable Sudoku (GAS) series.) Each
line is this intriguing puzzle is connecting pairs of factors, so thinking
of...
2 hours ago