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I was inspired by this great question: Paint Eight Squares

Given a $5 \times 5$ grid of white squares, can you paint 11 of the squares black so that each white square is orthogonally adjacent to exactly two black squares?

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The answer is

yes

and here's why:

5x5 grid with some cells colored black

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    $\begingroup$ That is correct! In fact this is the only solution I found and it is pretty. $\endgroup$ May 26 at 6:11
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    $\begingroup$ Pfft. That's cheating. "can you paint 11 of the squares black so that each white square is orthogonally adjacent to exactly two black squares?" yes, trivially, if none of the squares are white! :-) $\endgroup$
    – msh210
    May 26 at 14:59
  • $\begingroup$ they are white to Deusovi... $\endgroup$ May 26 at 15:15

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