From 0b90c1489828653bdec38db8dc824df560c4a0e5 Mon Sep 17 00:00:00 2001
From: Anna Wilson <annie.marie.mason@gmail.com>
Date: Sat, 7 May 2016 12:01:01 -0700
Subject: [PATCH 1/2] iterative solution

---
 hamming.rb      | 22 ++++++++++++++++++++++
 hamming_test.rb |  1 -
 2 files changed, 22 insertions(+), 1 deletion(-)
 create mode 100644 hamming.rb

diff --git a/hamming.rb b/hamming.rb
new file mode 100644
index 0000000..a4365c2
--- /dev/null
+++ b/hamming.rb
@@ -0,0 +1,22 @@
+class Hamming
+
+  def self.compute(seq1,seq2)
+    unless seq1.length == seq2.length
+      raise ArgumentError.new("The lengths of the strands must be equal.")
+    end
+
+    array1 = seq1.split(//)
+    array2 = seq2.split(//)
+    count = 0
+
+    array1.each_with_index do |item,index|
+      if item == array2[index]
+        count = count + 0
+      else
+        count = count + 1
+      end
+    end
+    return count
+  end
+  
+end
diff --git a/hamming_test.rb b/hamming_test.rb
index 2d1f9d7..f3feb79 100644
--- a/hamming_test.rb
+++ b/hamming_test.rb
@@ -4,7 +4,6 @@
 
 class HammingTest < Minitest::Test
   def test_identical_strands
-    skip
     assert_equal 0, Hamming.compute('A', 'A')
   end
 

From 94586d078e5c5ad2aa6cd33226f58b7f30e0c7aa Mon Sep 17 00:00:00 2001
From: Anna Wilson <annie.marie.mason@gmail.com>
Date: Sat, 7 May 2016 19:28:33 -0700
Subject: [PATCH 2/2] now with answer

---
 hamming.rb      | 36 +++++++++++++++++++++++++-----------
 hamming_test.rb | 13 -------------
 2 files changed, 25 insertions(+), 24 deletions(-)

diff --git a/hamming.rb b/hamming.rb
index a4365c2..5e1cf05 100644
--- a/hamming.rb
+++ b/hamming.rb
@@ -5,18 +5,32 @@ def self.compute(seq1,seq2)
       raise ArgumentError.new("The lengths of the strands must be equal.")
     end
 
-    array1 = seq1.split(//)
-    array2 = seq2.split(//)
-    count = 0
+    @array1 = seq1.split(//)
+    @array2 = seq2.split(//)
+    @count = 0
+    next_elements
+    count_differences(@element1,@element2)
+  end
+
+  def self.count_differences(element1,element2)
+    if @element1 == nil
+      return @count
+    end
 
-    array1.each_with_index do |item,index|
-      if item == array2[index]
-        count = count + 0
-      else
-        count = count + 1
-      end
+    if element1 != element2
+      @count += 1
+      next_elements
+      count_differences(@element1,@element2)
+    else
+      @count += 0
+      next_elements
+      count_differences(@element1,@element2)
     end
-    return count
   end
-  
+
+  def self.next_elements
+    @element1 = @array1.shift
+    @element2 = @array2.shift
+  end
+
 end
diff --git a/hamming_test.rb b/hamming_test.rb
index f3feb79..0ddf0a1 100644
--- a/hamming_test.rb
+++ b/hamming_test.rb
@@ -8,67 +8,54 @@ def test_identical_strands
   end
 
   def test_long_identical_strands
-    skip
     assert_equal 0, Hamming.compute('GGACTGA', 'GGACTGA')
   end
 
   def test_complete_distance_in_single_nucleotide_strands
-    skip
     assert_equal 1, Hamming.compute('A', 'G')
   end
 
   def test_complete_distance_in_small_strands
-    skip
     assert_equal 2, Hamming.compute('AG', 'CT')
   end
 
   def test_small_distance_in_small_strands
-    skip
     assert_equal 1, Hamming.compute('AT', 'CT')
   end
 
   def test_small_distance
-    skip
     assert_equal 1, Hamming.compute('GGACG', 'GGTCG')
   end
 
   def test_small_distance_in_long_strands
-    skip
     assert_equal 2, Hamming.compute('ACCAGGG', 'ACTATGG')
   end
 
   def test_non_unique_character_in_first_strand
-    skip
     assert_equal 1, Hamming.compute('AGA', 'AGG')
   end
 
   def test_non_unique_character_in_second_strand
-    skip
     assert_equal 1, Hamming.compute('AGG', 'AGA')
   end
 
   def test_large_distance
-    skip
     assert_equal 4, Hamming.compute('GATACA', 'GCATAA')
   end
 
   def test_large_distance_in_off_by_one_strand
-    skip
     assert_equal 9, Hamming.compute('GGACGGATTCTG', 'AGGACGGATTCT')
   end
 
   def test_empty_strands
-    skip
     assert_equal 0, Hamming.compute('', '')
   end
 
   def test_disallow_first_strand_longer
-    skip
     assert_raises(ArgumentError) { Hamming.compute('AATG', 'AAA') }
   end
 
   def test_disallow_second_strand_longer
-    skip
     assert_raises(ArgumentError) { Hamming.compute('ATA', 'AGTG') }
   end
 end