From 6b507bc436a6d9134111f49abbd7b4a99aa114a0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ga=C3=ABl=20Depreeuw?= <gael.depreeuw@scioteq.com>
Date: Wed, 4 Dec 2019 10:11:44 +0100
Subject: [PATCH] Day 4

---
 app/Main.hs |  5 +++++
 src/Day4.hs | 29 +++++++++++++++++++++++++++++
 2 files changed, 34 insertions(+)
 create mode 100644 src/Day4.hs

diff --git a/app/Main.hs b/app/Main.hs
index fc76977..7d95a8f 100644
--- a/app/Main.hs
+++ b/app/Main.hs
@@ -3,6 +3,7 @@ module Main where
 import Day1
 import Day2
 import Day3
+import Day4
 import System.IO
 import Data.List.Split
 import Data.Set
@@ -41,4 +42,8 @@ main = do
     r_day3 <- readFile "./app/input_day3"
     putStr "[Day 3] Result: "
     print $ getDistanceAndSteps r_day3
+    putStr "[Day 4-1] Result: "
+    print getNumberOfPasswords
+    putStr "[Day 4-2] Result: "
+    print getNumberOfPasswords'
 
diff --git a/src/Day4.hs b/src/Day4.hs
new file mode 100644
index 0000000..2311e8f
--- /dev/null
+++ b/src/Day4.hs
@@ -0,0 +1,29 @@
+module Day4
+    (
+      getNumberOfPasswords
+    , getNumberOfPasswords'
+    ) where
+
+import Data.List
+
+generatePasswords_Part1 :: [Integer]
+generatePasswords_Part1 =
+    [ x | x <- [145852..616942]
+        , has2Same (show x)
+        , increases ((read :: String -> Integer) . (:[]) <$> show x)]
+    where
+        has2Same xs = let ys = zip xs (tail xs ++ " ") in
+            any (uncurry (==)) ys
+        increases [] = True
+        increases xs = let ys = zip xs (tail xs ++ [maximum xs]) in
+            all (uncurry (<=)) ys
+
+getNumberOfPasswords :: Int
+getNumberOfPasswords = length generatePasswords_Part1
+
+generatePasswords_Part2 :: [Integer]
+generatePasswords_Part2 = filter f generatePasswords_Part1
+    where f x = 2 `elem` (length <$> group (show x))
+
+getNumberOfPasswords' :: Int
+getNumberOfPasswords' = length generatePasswords_Part2
\ No newline at end of file