day 15 (again, slow)

2022/day15.hs

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+import Data.List.Split (splitOn)
+import qualified Data.Set as S
+
+type Coord = (Int, Int)
+
+globalY :: Int
+globalY = 2000000
+
+parseCoord :: String -> Coord
+parseCoord xs = (read $ init x, read y) where
+    [x,y] = map (drop 2) $ splitOn " " xs
+
+parseLine :: String -> (Coord, Coord)
+parseLine xs = (sensor, beacon) where
+    [sensor, beacon] = map (parseCoord . dropWhile (/='x'))$ splitOn ":" xs
+
+manhattan :: Coord -> Coord -> Int
+manhattan (a,b) (x,y) = abs (a-x) + abs (b-y)
+
+allWithinRange :: Coord -> Coord -> S.Set Coord
+allWithinRange sensor@(a,b) beacon@(x,y) = S.fromList $ filter (\c -> manhattan sensor c <= dist) all where
+    minx = a - dist
+    maxx = a + dist
+    miny = b - dist
+    maxy = b + dist
+    dist = manhattan sensor beacon
+    all = [(x,y) | x <- [minx..maxx], y <- [globalY]]
+
+main :: IO ()
+main = do
+    x <- map parseLine . lines <$> getContents
+
+    let beacons = S.fromList $ map snd x
+    let reachable = foldr1 S.union $ map (uncurry allWithinRange) x
+
+    let ys = S.size $ S.filter (\x -> snd x == globalY) (reachable S.\\ beacons)
+
+    putStr "part 1: "
+    print ys

2022/inputs/day15

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+Sensor at x=2483411, y=3902983: closest beacon is at x=2289579, y=3633785
+Sensor at x=3429446, y=303715: closest beacon is at x=2876111, y=-261280
+Sensor at x=666423, y=3063763: closest beacon is at x=2264411, y=2779977
+Sensor at x=3021606, y=145606: closest beacon is at x=2876111, y=-261280
+Sensor at x=2707326, y=2596893: closest beacon is at x=2264411, y=2779977
+Sensor at x=3103704, y=1560342: closest beacon is at x=2551409, y=2000000
+Sensor at x=3497040, y=3018067: closest beacon is at x=3565168, y=2949938
+Sensor at x=1708530, y=855013: closest beacon is at x=2551409, y=2000000
+Sensor at x=3107437, y=3263465: closest beacon is at x=3404814, y=3120160
+Sensor at x=2155249, y=2476196: closest beacon is at x=2264411, y=2779977
+Sensor at x=3447897, y=3070850: closest beacon is at x=3404814, y=3120160
+Sensor at x=2643048, y=3390796: closest beacon is at x=2289579, y=3633785
+Sensor at x=3533132, y=3679388: closest beacon is at x=3404814, y=3120160
+Sensor at x=3683790, y=3017900: closest beacon is at x=3565168, y=2949938
+Sensor at x=1943208, y=3830506: closest beacon is at x=2289579, y=3633785
+Sensor at x=3940100, y=3979653: closest beacon is at x=2846628, y=4143786
+Sensor at x=3789719, y=1225738: closest beacon is at x=4072555, y=1179859
+Sensor at x=3939775, y=578381: closest beacon is at x=4072555, y=1179859
+Sensor at x=3880152, y=3327397: closest beacon is at x=3404814, y=3120160
+Sensor at x=3280639, y=2446475: closest beacon is at x=3565168, y=2949938
+Sensor at x=2348869, y=2240374: closest beacon is at x=2551409, y=2000000
+Sensor at x=3727441, y=2797456: closest beacon is at x=3565168, y=2949938
+Sensor at x=3973153, y=2034945: closest beacon is at x=4072555, y=1179859
+Sensor at x=38670, y=785556: closest beacon is at x=311084, y=-402911
+Sensor at x=3181909, y=2862960: closest beacon is at x=3565168, y=2949938
+Sensor at x=3099490, y=3946226: closest beacon is at x=2846628, y=4143786

2022/inputs/day15.test

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+Sensor at x=2, y=18: closest beacon is at x=-2, y=15
+Sensor at x=9, y=16: closest beacon is at x=10, y=16
+Sensor at x=13, y=2: closest beacon is at x=15, y=3
+Sensor at x=12, y=14: closest beacon is at x=10, y=16
+Sensor at x=10, y=20: closest beacon is at x=10, y=16
+Sensor at x=14, y=17: closest beacon is at x=10, y=16
+Sensor at x=8, y=7: closest beacon is at x=2, y=10
+Sensor at x=2, y=0: closest beacon is at x=2, y=10
+Sensor at x=0, y=11: closest beacon is at x=2, y=10
+Sensor at x=20, y=14: closest beacon is at x=25, y=17
+Sensor at x=17, y=20: closest beacon is at x=21, y=22
+Sensor at x=16, y=7: closest beacon is at x=15, y=3
+Sensor at x=14, y=3: closest beacon is at x=15, y=3
+Sensor at x=20, y=1: closest beacon is at x=15, y=3