solved part 2

day02/solution.rb

@@ -1,13 +1,40 @@
 #!/bin/env ruby
 
+#part 1
 ids = File.readlines('./input').map(&:strip)
 checksum = {twos: 0, threes: 0}
 
-ids.map! { |id| id.each_char.tally.delete_if { |char, count| count==1 }}
-ids.each do |id|
+chars = ids.map { |id| id.each_char.tally.delete_if { |char, count| count==1 }}
+chars.each do |id|
     checksum[:twos] += 1 if id.has_value?(2)
     checksum[:threes] += 1 if id.has_value?(3)
 end
 
 puts checksum[:twos] * checksum[:threes]
 
+#part 2
+stop = false
+count = 0
+match = []
+ids.each do |id|
+    ids.each do |id2|
+        next if id == id2
+        count = 0
+        id.each_char.with_index do |char, i|
+            count += 1 if char != id2[i]
+            break if count > 1
+        end
+        if count == 1
+            puts id2
+            match.push(id2)
+            break
+        end
+    end
+    if count ==1
+        puts id
+        match.push(id)
+        break
+    end
+end
+
+puts (match[0].chars & match[1].chars).join