From 9052fd9db6e534f0c01f2feecc19d57f086af335 Mon Sep 17 00:00:00 2001
From: Jonathan Chan <jonathanhwchan@gmail.com>
Date: Tue, 12 Dec 2017 09:28:43 -0800
Subject: [PATCH] Day 6, part 1

---
 6.hs  | 37 +++++++++++++++++++++++++++++++++++++
 6.txt |  1 +
 2 files changed, 38 insertions(+)
 create mode 100644 6.hs
 create mode 100644 6.txt

diff --git a/6.hs b/6.hs
new file mode 100644
index 0000000..79f67c4
--- /dev/null
+++ b/6.hs
@@ -0,0 +1,37 @@
+import Data.Foldable
+import Data.HashSet
+import Data.Sequence
+
+type Bank   = Seq Int
+type Config = (Bank, Data.HashSet.HashSet [Int])
+
+(%) :: Int -> Int -> Int
+(%) = mod
+
+getMaxMem :: Bank -> (Int, Int)
+getMaxMem bank =
+    foldlWithIndex (\(currIndex, currMax) index value -> if value > currMax then (index, value) else (currIndex, currMax)) (0, 0) bank
+
+nextBank :: Bank -> Bank
+nextBank bank =
+    let len = Data.Sequence.length bank
+        (index, value) = getMaxMem bank
+        zeroedBank = update index 0 bank
+        mappedBank = fmap (+ value `div` len) zeroedBank
+        indicesToUpdate = fmap (% len) [(index + 1)..(index + value % len)]
+    in  mapWithIndex (\i v -> if i `elem` indicesToUpdate then v + 1 else v) mappedBank
+
+
+cycles :: Int -> Config -> Int
+cycles count (prevBank, configs) =
+    let bank = nextBank prevBank
+        hashableBank    = Data.Foldable.toList bank
+    in  if   member hashableBank configs
+        then count + 1
+        else cycles (count + 1) (bank, insert hashableBank configs)
+
+main :: IO ()
+main = do
+    input <- readFile "6.txt"
+    let bank = Data.Sequence.fromList $ fmap read $ words input :: Bank
+    print $ cycles 0 (bank, Data.HashSet.empty)
diff --git a/6.txt b/6.txt
new file mode 100644
index 0000000..bb545e3
--- /dev/null
+++ b/6.txt
@@ -0,0 +1 @@
+14	0	15	12	11	11	3	5	1	6	8	4	9	1	8	4
\ No newline at end of file