7-2

1 files changed, 25 insertions, 0 deletions

diff --git a/7-2.hs b/7-2.hs
new file mode 100644
index 0000000..f191196
--- /dev/null
+++ b/7-2.hs
@@ -0,0 +1,25 @@
+cat :: Int -> Int -> Int
+cat x y = x * 10^(floor (logBase 10 (fromIntegral y)) + 1) + y
+
+combine :: [Int] -> [Int]
+combine (x:xs) = foldl f [x] xs
+  where
+    f :: [Int] -> Int -> [Int]
+    f ns n = [(+), (*), cat] <*> ns <*> [n]
+
+check :: Int -> [Int] -> Bool
+check x xs = elem x (combine xs)
+
+parseLine :: String -> (Int,[Int])
+parseLine s = (read $ init x, map read xs)
+  where
+    (x:xs) = words s
+
+result :: [(Int,[Int])] -> Int
+result xs = sum . map fst . filter snd
+  $ zip (map fst xs) (map (uncurry check) xs)
+
+main :: IO ()
+main = do
+  ls <- lines <$> getContents
+  print . result . map parseLine $ ls