From a07b6fba16eb091904f3c3d00c3a5e3636e36ce2 Mon Sep 17 00:00:00 2001
From: shu <shu@lain.localdomain>
Date: Wed, 4 Dec 2019 08:02:39 +0100
Subject: [PATCH] Day 4: Initial version

Now to look at other solutions
---
 2019/day4/day4.hs | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)
 create mode 100644 2019/day4/day4.hs

diff --git a/2019/day4/day4.hs b/2019/day4/day4.hs
new file mode 100644
index 0000000..bc5fd91
--- /dev/null
+++ b/2019/day4/day4.hs
@@ -0,0 +1,28 @@
+import Data.List
+
+main = do
+    let bottom = 130254
+    let top = 678275
+    print (day4a bottom top)
+    print (day4b bottom top)
+
+day4a bottom top = dumbbrute bottom top p 0
+day4b bottom top = dumbbrute bottom top p' 0
+
+dumbbrute x y p acc
+    | x'<=y = dumbbrute x' y p (if p (numexpl x) then acc+1 else acc)
+    | otherwise = acc
+    where x' = succ x
+
+p x
+    | sort x /= x = False
+    | nub x == x = False
+    | otherwise = True
+
+p' x
+    | sort x /= x = False
+    | 2 `elem` (map length $ group x) = True
+    | otherwise = False
+
+numexpl 0 = []
+numexpl x = numexpl (x `div` 10) ++ [x `mod` 10]