From 19975730a539af00664d6b8a067f943cceb7ee2a Mon Sep 17 00:00:00 2001
From: Martin Potier <martin.potier@marvid.fr>
Date: Mon, 7 Dec 2020 12:11:12 +0200
Subject: [PATCH] Day 5 - Part 2

---
 day5/main.hs | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/day5/main.hs b/day5/main.hs
index 6dceeaa..c1370d9 100755
--- a/day5/main.hs
+++ b/day5/main.hs
@@ -6,6 +6,7 @@
 {-# LANGUAGE OverloadedStrings #-}
 
 -- import Debug.Trace (trace)
+import Data.List (sort)
 
 binaryPartitionWalker :: String -> Int -> Int -> (String, Int, Int)
 binaryPartitionWalker ('F':s) begin end =
@@ -29,6 +30,9 @@ seatID str = row * 8 + seat
 solvePart1 :: [String] -> Int
 solvePart1 = maximum . (map seatID)
 
+solvePart2 :: [String] -> Int
+solvePart2 = fst . head . (filter (\(x,y) -> x /= y)) . (zip [13..]) . sort . (map seatID)
+
 main :: IO ()
 main = do
   putStrLn "Day 5 - Part 1"
@@ -36,6 +40,8 @@ main = do
   print $ seatID "BFFFBBFRRR"
   print $ seatID "FFFBBBFRRR"
   print $ seatID "BBFFBBFRLL"
-  putStrLn $ "Solution of part 1"
   input <- lines <$> readFile "day5/input"
+  putStrLn $ "Solution of part 1"
   print $ solvePart1 input
+  putStrLn $ "Solution of part 2"
+  print $ solvePart2 input