From 325e3fa7af74449bbdb2048f5e20684ba6019095 Mon Sep 17 00:00:00 2001
From: Yuchen Pei <me@ypei.me>
Date: Mon, 11 Dec 2017 15:32:00 +0100
Subject: finished day 11, finished day 10 part 1

---
 Puzzle10.hs | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)
 create mode 100644 Puzzle10.hs

(limited to 'Puzzle10.hs')

diff --git a/Puzzle10.hs b/Puzzle10.hs
new file mode 100644
index 0000000..4909eac
--- /dev/null
+++ b/Puzzle10.hs
@@ -0,0 +1,31 @@
+import Data.List.Split (splitOn)
+
+split3Ways :: [Int] -> Int -> Int -> ([Int], [Int], [Int])
+split3Ways xs from to
+  | to >= from = (take from xs, take (to - from) (drop from xs), drop to xs)
+  | otherwise = split3Ways xs to from
+
+permute :: [Int] -> Int -> Int -> [Int]
+permute xs from to 
+  | to >= from = xs1 ++ reverse xs2 ++ xs3
+  | otherwise = xs1' ++ xs2 ++ xs3'
+      where (xs1, xs2, xs3) = split3Ways xs from to
+            xs4 = reverse (xs3 ++ xs1)
+            (xs3', xs1') = splitAt (length xs3) xs4
+
+step :: ([Int], Int, Int) -> Int -> ([Int], Int, Int)
+step (xs, skip, from) n = let m = length xs in 
+  (permute xs from ((from + n) `mod` m), skip + 1, (from + n + skip) `mod` m)
+
+solve1' :: [Int] -> Int
+solve1' xs = let (ys, _, _) = foldl step ([0 .. 255], 0, 0) xs in
+--solve1' xs = let (ys, _, _) = foldl step ([0 .. 4], 0, 0) xs in
+  (head ys) * (head $ tail ys)
+
+parseInput :: [Char] -> [Int]
+parseInput = (fmap read) . (splitOn ",")
+
+solve1 :: [Char] -> Int
+solve1 = solve1' . parseInput
+
+input = "120,93,0,90,5,80,129,74,1,165,204,255,254,2,50,113"
-- 
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