Thursday, 3 July 2025

Freddie Hand

This year's World Puzzle Championship is due to take place in Eger, Hungary. I was taking a look through the 2011 WPC which is the most recent Hungarian championship, also in Eger. Circular Reasoning stood out with its very simple ruleset (though I have altered the rules a little for this GAPP!)

You might be wondering why the main puzzle isn't 10 by 10. I'll phrase the answer in terms of a puzzle: Suppose an n by m grid can be tiled with L tetrominoes. Prove that 8 divides nm.

Rules: Divide the grid into L tetrominoes such that each L tetromino contains exactly two circles. (An L tetromino is shape of 4 cells that looks like an L - see the example solution)

Rules Note: Strictly speaking, the original rules state "Divide the grid into L-shapes of the same size such that each L-shape contains 2 circles". Both puzzles work under this ruleset because you can work out the size each L-shape needs to be by counting the number of circles - I've decided to save you that effort.

Solving Note: Answer check is enabled for either edges or lines (you don't need to draw both). If you're on mobile you might want to switch from composite to pure edge or pure line.

Acquire a Speedy Sloth 🦥 by solving the puzzle in 1:30 or less!
Obtain a Quick Crab 🦀 by solving the puzzle in 3:00 or less!
And all solvers who complete the puzzle will be rewarded with a Hungarian Hunter's Cisticola 🐦

Example (Penpa+): https://tinyurl.com/249moxe6
Puzzle (Penpa+): https://tinyurl.com/269zv4kn