1 files changed, 15 insertions, 0 deletions
diff --git a/05/b.rb b/05/b.rb
new file mode 100644
index 0000000..378f7c6
--- /dev/null
+++ b/05/b.rb
@@ -0,0 +1,15 @@
+missing = 0
+File.readlines('input.txt').map do |line|
+  line.tr('FBLR', '0101')
+end.map do |line|
+  row = line.slice(0, 7).to_i 2
+  seat = line.slice(7, 3).to_i 2
+  row * 8 + seat
+end.sort.reduce do |last_seen, current|
+  if current - 1 != last_seen
+    missing = current - 1
+  end
+  current
+end
+
+puts missing