1 files changed, 15 insertions, 0 deletions
diff --git a/day03/part2.rb b/day03/part2.rb
new file mode 100644
index 0000000..baaecb9
--- /dev/null
+++ b/day03/part2.rb
@@ -0,0 +1,15 @@
+def priority(ch)
+  if ch >= ?a && ch <= ?z
+    ch.ord - 96
+  elsif ch >= ?A && ch <= ?Z
+    ch.ord - 64 + 26
+  end
+end
+
+backpacks = $stdin.readlines.map(&:strip).map(&:chars)
+
+commons = backpacks.each_slice(3).map do |backpacks|
+  backpacks.inject(:&)[0]
+end
+
+puts commons.map{|ch|priority(ch)}.sum