1 files changed, 29 insertions, 0 deletions
diff --git a/2020/10a.hs b/2020/10a.hs
new file mode 100644
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--- /dev/null
+++ b/2020/10a.hs
@@ -0,0 +1,29 @@
+module Day10A where
+
+import System.Environment (getArgs)
+import Data.List (sort)
+
+-- Get the longest chain of adapters possible
+getJoltsChain :: [Int] -> [Int]
+getJoltsChain ss = xs ++ [last xs + 3]
+                where xs = sort ss
+
+-- Read a line-seperated file of numbers
+numsFromFile :: String -> IO [Int]
+numsFromFile p = do
+                    c <- readFile p;
+                    return $ map read $ lines c; 
+
+main :: IO ()
+main = do 
+        args <- getArgs;
+        xs <- numsFromFile $ head args;
+
+        let chain = 0 : getJoltsChain xs;
+
+        let diffs = zipWith (-) chain (drop 1 chain);
+        let diff3s = length $ filter (== -3) diffs;
+        let diff1s = length $ filter (== -1) diffs;
+
+        print $ diff1s * diff3s;
+        return ();