finished recursion

hamming.rb

@@ -0,0 +1,25 @@
+ # Hamming Test Project
+class Hamming
+
+  def self.compute(str1, str2)
+    puts "str1 = #{str1}, str2 = #{str2}"
+    # Base case: no more characters to process / empty string
+    return 0 if str1.length <= 0 # str1 == "" , str1.empty?
+
+    # Recursive case: peel off one letter, recurse, and add 1 if different
+    first = str1[0]
+    second = str2[0]
+    if first != second
+      puts "First letters are different"
+      return 1 + compute(str1[1..-1],str2[1..-1])
+    else
+      return 0 + compute(str1[1..-1],str2[1..-1])
+    end
+
+  end
+
+end
+
+#str1('AT') = 1
+#str2('CT') = 1
+puts Hamming.compute("ATGAC","ACTAC")

hamming1.rb

@@ -0,0 +1,20 @@
+# Hamming Test Project
+class Hamming
+
+  def self.compute(str1, str2)
+    # hamming distance assumes strings of equal length
+    # .chars splits a string into an array
+    str1 = str1.chars
+    str2 = str2.chars
+
+    raise ArgumentError unless str1.length == str2.length #error when user makes an arror, not an error with syntax
+
+    differences = 0
+    str1.each_index do |ind|
+        if str1[ind] != str2[ind]
+          differences += 1
+        end
+      end
+      return differences
+  end
+end

hamming_test.rb

@@ -4,7 +4,6 @@
 
 class HammingTest < Minitest::Test
   def test_identical_strands
-    skip
     assert_equal 0, Hamming.compute('A', 'A')
   end