add day10

1 files changed, 29 insertions, 0 deletions

diff --git a/execs/Day10.hs b/execs/Day10.hs
new file mode 100644
index 0000000..c42a550
--- /dev/null
+++ b/execs/Day10.hs
@@ -0,0 +1,29 @@
+
+module Main where
+
+import Utils
+import Data.List (sort)
+import Control.Monad
+import Control.Monad.Memo
+
+parseLine :: String -> Int
+parseLine = read
+
+diffs :: [Int] -> Int
+diffs s = product $ ($ q s) <$> [howMany (==1), howMany (==3)]
+    where q = zipWith subtract `ap` tail
+
+combos top s = startEvalMemo $ go 0
+    where go c
+            | c == top = return 1
+            | otherwise = do
+                let cs = filter (`elem` s) $ map (+c) [1,2,3]
+                sum <$> mapM (memo go) cs
+
+main :: IO ()
+main = do
+    n <- map parseLine . lines <$> readFile "input/10"
+    let top = maximum n + 3
+        ls = sort (0:top:n)
+    print $ diffs ls
+    print $ combos top ls