From 43476314d72320bf434f7c12178ece1c7f39e80c Mon Sep 17 00:00:00 2001
From: Quinten Kock <quintenkock@gmail.com>
Date: Sat, 18 Dec 2021 09:26:21 +0100
Subject: [PATCH] day17 and day18

---
 2021/day17.hs           |  36 +++++++++++++++
 2021/day18.hs           |  86 ++++++++++++++++++++++++++++++++++
 2021/inputs/day18.input | 100 ++++++++++++++++++++++++++++++++++++++++
 3 files changed, 222 insertions(+)
 create mode 100644 2021/day17.hs
 create mode 100644 2021/day18.hs
 create mode 100644 2021/inputs/day18.input

diff --git a/2021/day17.hs b/2021/day17.hs
new file mode 100644
index 0000000..9da9f49
--- /dev/null
+++ b/2021/day17.hs
@@ -0,0 +1,36 @@
+module Day17 where
+
+import Debug.Trace (trace)
+
+xmin = 111
+xmax = 161
+ymin = -154
+ymax = -101
+
+x_vel_to_pos :: Int -> Int
+x_vel_to_pos 0 = 0
+x_vel_to_pos x = x + (x_vel_to_pos (x-1))
+
+x_vel :: Int
+x_vel = head $ filter (\x -> let pos = x_vel_to_pos x in pos >= xmin && pos <= xmax) $ [0..]
+
+max_y :: Int -> Int
+max_y yv = go yv 0 where
+    go vel pos = if vel <= 0 then pos else go (vel-1) (pos+vel)
+
+
+x_y_reaches :: Int -> Int -> Int -> Int -> Bool
+x_y_reaches xv yv x y
+    | x >= xmin && x <= xmax && y >= ymin && y <= ymax = True
+    | y < ymin || x > xmax = False
+    | otherwise = x_y_reaches (max (xv-1) 0) (yv-1) (x+xv) (y+yv)
+
+try_y :: [Int]
+try_y = filter (\yv -> x_y_reaches x_vel yv 0 0) [0..250]
+
+try_x_y :: Int -> [Int]
+try_x_y xv = filter (\yv -> x_y_reaches xv yv 0 0) [-250..250]
+
+main :: IO ()
+main = do
+    print "bye"
diff --git a/2021/day18.hs b/2021/day18.hs
new file mode 100644
index 0000000..1cf396f
--- /dev/null
+++ b/2021/day18.hs
@@ -0,0 +1,86 @@
+module Day18 where
+import Data.Char (isDigit, digitToInt)
+import Data.List (foldl')
+
+data Number = Single Int | Pair Number Number deriving (Eq)
+
+instance Show Number where
+  show (Single x) = show x
+  show (Pair x y) = '[':show x ++ ',':show y ++ "]"
+
+replaceRight :: Int -> Number -> Number
+replaceRight y (Single x) = Single (x+y)
+replaceRight y (Pair l r) = Pair l (replaceRight y r)
+
+replaceLeft :: Int -> Number -> Number
+replaceLeft y (Single x) = Single (x+y)
+replaceLeft y (Pair l r) = Pair (replaceLeft y l) r
+
+explode :: Int -> Number -> (Maybe Int, Maybe Int, Number)
+explode _ (Single x) = (Nothing, Nothing, Single x)
+explode 4 (Pair (Single x) (Single y)) = (Just x, Just y, Single 0)
+explode 4 _ = error "pairs that are deeper than 4"
+explode lvl (Pair x y)
+        | ln /= x = case lr of
+                Nothing  -> (ll, Nothing, Pair ln y)
+                (Just r) -> (ll, Nothing, Pair ln (replaceLeft r y))
+        | otherwise = case rl of
+                Nothing  -> (Nothing, rr, Pair x rn)
+                (Just l) -> (Nothing, rr, Pair (replaceRight l x) rn)
+        where
+                (ll, lr, ln) = explode (lvl+1) x
+                (rl, rr, rn) = explode (lvl+1) y
+
+explodeFull :: Number -> Number
+explodeFull n = let (_,_,new) = explode 0 n in new
+
+split :: Number -> Number
+split (Single x)
+        | x > 9 = Pair (Single $ x `div` 2) (Single $ (x+1) `div` 2)
+        | otherwise = Single x
+split (Pair x y) = if split x /= x then Pair (split x) y else Pair x (split y)
+
+reduce :: Number -> (Number, Bool)
+reduce n
+  | n /= exploded = (exploded, True)
+  | n /= splitN = (splitN, True)
+  | otherwise = (n, False)
+  where
+      exploded = explodeFull n
+      splitN = split n
+
+reduceFull :: Number -> Number
+reduceFull n = fst $ until (not . snd) (reduce . fst) (n, True)
+
+parse :: String -> (Number, String)
+parse [] = error "parsing empty string"
+parse ('[': xs) = (Pair l r, xs'') where
+                (l, ',':xs') = parse xs
+                (r, ']':xs'') = parse xs'
+parse (x:xs)
+        | isDigit x = (Single $ digitToInt x, xs) -- yes i know this only works for single-digit numbers
+        | otherwise = error "parse error"
+
+add :: Number -> Number -> Number
+add = Pair
+
+addAll :: [Number] -> Number
+addAll [] = error "sum of empty list"
+addAll (x:xs) = foldl' (\s i -> reduceFull (s `add` i)) x xs
+
+magnitude :: Number -> Int
+magnitude (Single x) = x
+magnitude (Pair l r) = (magnitude l * 3) + (magnitude r * 2)
+
+main :: IO ()
+main = do
+        nums <- map (fst . parse) . lines <$> getContents
+        print $ addAll nums
+
+        putStr "part 1: "
+        print $ magnitude $ addAll nums
+
+        putStr "part 2: " -- please use compiled code!
+        let m = maximum $ map (\n1 -> maximum $ map (\n2 ->
+                magnitude $ reduceFull (n1 `add` n2)) nums) nums
+        print m
diff --git a/2021/inputs/day18.input b/2021/inputs/day18.input
new file mode 100644
index 0000000..47ba5f8
--- /dev/null
+++ b/2021/inputs/day18.input
@@ -0,0 +1,100 @@
+[[7,[8,[3,5]]],[[[3,6],9],1]]
+[[[[1,7],8],[0,4]],[[[0,9],2],[2,[5,6]]]]
+[[[4,[4,4]],[8,[4,4]]],[[5,4],6]]
+[[[1,[1,3]],[[9,6],1]],[[4,[5,4]],[[4,4],[0,8]]]]
+[[[[6,2],[2,5]],[2,1]],[[1,5],7]]
+[[[[5,0],[2,7]],[[2,5],2]],[2,[3,2]]]
+[[[6,[6,6]],[0,[2,8]]],[[8,[5,6]],[4,5]]]
+[[[6,[3,5]],8],[[2,[7,0]],5]]
+[[[[7,8],[3,6]],[1,6]],[[[4,2],1],[[0,7],[5,6]]]]
+[8,2]
+[[5,5],[[2,[9,1]],8]]
+[[[4,8],[[1,8],2]],[9,2]]
+[2,[[8,[8,3]],[0,6]]]
+[[[6,6],[[6,0],6]],[0,[[3,4],3]]]
+[[[[2,9],[5,9]],[2,[4,3]]],[6,0]]
+[[[6,2],0],[7,7]]
+[[[9,6],5],[2,[[0,1],[5,5]]]]
+[[6,[[0,1],[5,1]]],5]
+[4,[[[4,2],3],[2,[5,0]]]]
+[[[7,9],2],2]
+[[[5,[2,1]],1],[[1,1],[8,5]]]
+[[[[5,9],0],[[1,9],0]],4]
+[[7,[0,5]],[[0,3],[8,2]]]
+[[6,[9,[7,7]]],6]
+[2,[[1,[1,0]],[4,[6,1]]]]
+[[0,6],[[[5,1],6],[[4,7],[8,0]]]]
+[[[1,[4,7]],[0,[1,2]]],[[1,1],[[1,2],[1,3]]]]
+[[8,[3,0]],[3,[1,[8,1]]]]
+[[[7,[4,0]],[[8,7],2]],[[7,[7,3]],7]]
+[3,[[1,7],2]]
+[8,[[[1,5],0],1]]
+[[6,[1,4]],7]
+[[[[2,6],2],8],1]
+[9,7]
+[9,[[[1,1],1],[[3,0],[7,3]]]]
+[[[[8,5],7],[[5,1],[6,4]]],[4,[[7,6],[2,7]]]]
+[[[[8,7],1],0],[[9,9],[[1,0],8]]]
+[[9,[[1,1],7]],[[3,0],4]]
+[[[[8,2],4],[9,[7,9]]],[[0,2],[[3,0],5]]]
+[[[[3,6],3],[[9,7],[0,6]]],[[[4,9],[1,3]],[2,[7,3]]]]
+[[[[3,8],0],[[3,6],5]],[[3,[4,2]],[[6,1],[8,5]]]]
+[[2,7],[[0,0],8]]
+[[[[0,3],7],[2,0]],3]
+[[0,2],[[[3,1],0],[0,0]]]
+[[[[6,1],7],[[8,4],[2,4]]],[[1,6],[2,3]]]
+[[2,[2,[9,1]]],[4,[[0,4],9]]]
+[[[3,[5,6]],7],1]
+[[[3,0],[8,[9,3]]],[[[1,1],1],[6,7]]]
+[[[6,[4,4]],[[1,9],1]],[[[8,1],[9,8]],[[6,3],1]]]
+[[[5,8],[[0,3],[1,7]]],[[[3,2],[4,7]],1]]
+[[5,5],[[[8,3],[6,6]],2]]
+[[[[1,9],[8,5]],[[7,7],8]],[0,[8,[7,4]]]]
+[[6,[4,[4,3]]],[5,[6,[7,2]]]]
+[[0,[[9,0],0]],5]
+[[[[5,6],[1,3]],[[0,5],[7,5]]],[[[0,4],[3,6]],[8,[3,6]]]]
+[[3,[[4,7],[7,0]]],[[[4,1],5],[[6,6],[7,4]]]]
+[[[[4,3],[0,1]],[[7,3],[2,3]]],[[[3,7],[2,2]],[6,5]]]
+[[1,1],[[[1,4],6],[6,[3,9]]]]
+[[[[0,8],[2,0]],5],[4,[[6,1],[2,1]]]]
+[[7,[3,[7,2]]],[[7,9],8]]
+[[[4,[9,8]],[8,[3,2]]],[7,9]]
+[[[4,[4,2]],[5,[0,3]]],[[[4,9],[2,9]],[[1,5],[0,8]]]]
+[[1,[[9,8],0]],[5,[[4,3],5]]]
+[[[[5,1],3],[[2,9],[9,0]]],[1,[6,3]]]
+[[[6,4],[6,1]],7]
+[[4,8],[[7,2],6]]
+[[[5,[4,8]],[[1,7],[2,8]]],[6,[[8,4],[3,5]]]]
+[[5,8],[[[4,0],[6,0]],[5,[6,0]]]]
+[[3,[[5,3],8]],[8,5]]
+[[[2,6],[1,[2,3]]],[[[1,7],[5,7]],[[0,0],[0,5]]]]
+[[0,[[4,3],[3,6]]],[[2,[6,6]],[0,[2,9]]]]
+[[[5,9],[6,2]],[[7,6],8]]
+[[9,2],[1,[[0,5],[5,0]]]]
+[[[3,1],[9,3]],3]
+[[[[2,0],[4,2]],6],[[[5,2],[7,8]],[[0,7],3]]]
+[[7,[[3,9],[6,3]]],[2,[[6,4],3]]]
+[[5,[3,[7,4]]],[[2,5],[0,9]]]
+[3,7]
+[[3,9],[[[4,4],9],[[3,1],7]]]
+[[[[4,0],1],[8,[3,6]]],[[9,[4,4]],[[9,9],9]]]
+[[8,[[8,1],5]],[[[9,1],4],[[8,5],3]]]
+[[6,[[6,3],[3,7]]],4]
+[[[1,[0,8]],9],[[8,5],[3,[0,5]]]]
+[[[[3,1],0],[[8,5],[1,0]]],[0,2]]
+[[2,[4,7]],2]
+[[[2,0],[2,2]],4]
+[4,[[5,8],5]]
+[[[2,[0,5]],[[3,3],[6,6]]],1]
+[[[2,[2,4]],[5,[7,1]]],[3,5]]
+[[2,[9,[3,9]]],9]
+[[[7,[7,1]],[[5,2],1]],[[2,1],[9,[7,3]]]]
+[[4,[4,6]],4]
+[[[4,2],[9,[3,8]]],[[2,4],0]]
+[[[7,[0,3]],4],[[[1,8],4],[[5,1],1]]]
+[[[1,3],3],[[4,9],[[0,0],6]]]
+[[[4,1],0],[[[5,6],[0,8]],[[2,1],1]]]
+[[3,[3,[7,9]]],[[[6,8],8],[[7,9],3]]]
+[[4,[[1,6],[4,6]]],[[1,8],[3,8]]]
+[[[[5,9],2],[[6,7],4]],3]
+[[[[2,1],[1,9]],7],[[[0,9],[0,5]],[[2,5],[5,0]]]]
\ No newline at end of file