Magnets
Puzzle: Magnets - AWAITING APPROVAL
Author: @VizGhar
Published Difficulty: Medium
Algorithm X Complexity:
Strategy
@VizGhar’s Magnets puzzle is a polarizing test of logic, where every decision attracts or repels another. You must fill the grid with polarized magnets and neutral wooden blocks. To keep the grid stable, no two orthogonal cells can share the same polarity — no two + cells or two – cells may touch. Each row and column must also satisfy its given counts of positive and negative poles.
A basic Algorithm X setup will get you most of the way there, but the toughest test cases require a bit of extra optimization — something you can approach in several ways. As you might expect by now, I chose a round of logical problem-space reduction that trimmed the hardest grids down to smaller, solvable cores that Algorithm X could finish effortlessly.
This puzzle is based on Magnets from Simon Tatham’s Portable Puzzle Collection. Logical deduction feels a bit more elusive here than in many other puzzles, but playing a few rounds by hand is a great way to uncover useful strategies and develop a stronger intuition for the puzzle’s magnetic dynamics.
Solving Logic Puzzles Logically
Many Magnets test cases and validators can be solved purely by logic, without a single guess. Click here to see my ongoing progress toward solving as many logic puzzles as possible—strictly with logic, no guessing, no backtracking.