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๐ŸŽ - 2025 DAY 9 SOLUTIONS - ๐ŸŽ (programming.dev)
submitted 11 months ago by to c/advent_of_code@programming.dev
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Day 9: Movie Theater

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[โ€“] 2 points 10 months ago (2 children)

My initial attempt on even-odd got me in trouble with the outline, as given, being 1 unit wide, not zero-width. I had to compute normals to find out outline around the tiles. You write "on the line -> outside" but don't many legal rectangle candidates sit on the edge?

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  • [โ€“] 2 points 10 months ago (1 child)

    On the line -> inside. The calculation I've done is a bit tricksy - vertical lines include the endpoints but horizontal lines exclude them, so that the even-odd rule is followed properly if you're on the same row as corners. No lines overlap.

    I'd considered using the dot product to work out whether the line turned left or right, but there's a lot of cases to consider and get right. Fair play on computing the normals.

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