solve: day 6

- solve: day 6, part 1
 - solve: day 6, part 2

2020/06/day6.hs

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+module Day6 (lines') where
+
+lines' = joinLines . lines
+
+joinLines = foldl parse [[]]
+  where 
+    parse [[]] s = [[s]]
+    parse [a] "" = [[], a]
+    parse [a] s = [a ++ [s]]
+    parse (a:as) s = parse [a] s ++ as

2020/06/part1.hs

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+#!/usr/bin/env runghc
+
+import Day6
+import Data.Set (fromList, size)
+
+main = interact (show . solve . parse)
+
+solve = sum . map size
+
+parse = map fromList . lines'

2020/06/part2.hs

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+#!/usr/bin/env runghc
+
+import Day6
+import Data.Set (fromList, size)
+
+main = interact (show . solve . parse)
+
+solve = sum . map countEveryoneYes
+
+parse = lines'
+
+countEveryoneYes :: [String] -> Int
+countEveryoneYes group =
+    length $ filter everyoneYes questions
+  where
+    n = length group
+    questions = ['a'..'z']
+    everyoneYes q = all (elem q) group