#74: Su Doku

XKCD comic, described below.
Transcript

[[A square divided into 2x2 squares, the top-right one has an 1 in it, the bottom-right one has a 0, the two left ones are empty]] [[Label: Binary Su Doku]] {{alt text: This one is from the Red Belt collection, of 'medium' difficulty.}}

This one is from the Red Belt collection, of 'medium' difficulty.

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