From bbd4254ce879d7c22721f8f560e41f609bd837e8 Mon Sep 17 00:00:00 2001
From: Zach Perrault <zach@perrault.email>
Date: Sun, 6 Dec 2020 12:05:40 -0500
Subject: [PATCH] solve: day 6, part 2 - bitwise

---
 2020/06/part2_bits.hs | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)
 create mode 100755 2020/06/part2_bits.hs

diff --git a/2020/06/part2_bits.hs b/2020/06/part2_bits.hs
new file mode 100755
index 0000000..fac165f
--- /dev/null
+++ b/2020/06/part2_bits.hs
@@ -0,0 +1,17 @@
+#!/usr/bin/env runghc
+
+
+import Day6
+import Data.Bits
+import Data.Char
+
+main = interact (show . solve . lines')
+
+solve = sum . map countEveryoneYes
+
+charToBit c = bit $ ord c - ord 'a'
+
+stringToBits :: String -> Int
+stringToBits str = foldl1 (.|.) $ map charToBit str
+
+countEveryoneYes group = popCount $ foldl1 (.&.) $ map stringToBits group