2025/1/p2.hs at main · eldridge.cam/advent-of-code

Advent of Code solutions

advent-of-code / 2025 / 1 / p2.hs

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 1rotate (count, rot) ('L' : dist) = rotate_ count rot (-read dist)
 2rotate (count, rot) ('R' : dist) = rotate_ count rot (read dist)
 3
 4rotate_ count rot dist = (count2, rot2)
 5  where
 6    rotations = abs dist `div` 100
 7    crossed = not $ (rot + dist `rem` 100) `elem` [0 .. 99]
 8    count2 = count + rotations + if crossed then 1 else 0
 9    rot2 = (rot + (dist `rem` 100) + 100) `rem` 100
10
11main = getContents >>= print . fst . foldl rotate (0, 50) . lines