diff --git a/lib/reverse_sentence.rb b/lib/reverse_sentence.rb
index 3fe7cac..b8a24e0 100644
--- a/lib/reverse_sentence.rb
+++ b/lib/reverse_sentence.rb
@@ -1,6 +1,50 @@
 # A method to reverse the words in a sentence, in place.
-# Time complexity: ?
-# Space complexity: ?
-def reverse_sentence(my_sentence)
-  raise NotImplementedError
+# Time complexity: O(n + m) - 
+# Reverse_Sentence
+#   - 1st while loop: O(.5n) where n is the number of letters
+#   - 2nd while loop: O(n) where n is the number of letters
+# Reverse
+#   - O(m): where m is the number of words
+# Space complexity: O(1)
+
+def reverse(text, text_start, text_end)
+  i = 0
+  ((text_end - text_start)/2).times do
+    temp_char = text[text_start + i]
+    text[text_start + i] = text[text_end - i - 1]
+    text[text_end - i - 1] = temp_char
+    i += 1
+  end
 end
+
+
+def reverse_sentence(my_sentence)
+  return nil if my_sentence.nil?
+  letter = 0
+  length = my_sentence.length
+  
+  end_char = length - 1
+  while letter < my_sentence.length/2 do
+    temp_char = my_sentence[letter]
+    my_sentence[letter] = my_sentence[length - 1 - letter]
+    my_sentence[length - 1 - letter] = temp_char
+    letter += 1
+  end
+  
+  letter = 0
+  while letter < my_sentence.length do
+    while my_sentence[letter] == " "
+      letter += 1
+    end  
+    start_index = letter
+    
+    while  my_sentence[letter] != " " && letter < my_sentence.length
+      letter += 1
+    end
+    end_index = letter
+    
+    reverse(my_sentence, start_index, end_index)    
+  end
+  
+  return my_sentence
+end
\ No newline at end of file
diff --git a/lib/sort_by_length.rb b/lib/sort_by_length.rb
index a5713ad..fa42b16 100644
--- a/lib/sort_by_length.rb
+++ b/lib/sort_by_length.rb
@@ -1,7 +1,22 @@
 # A method which will return an array of the words in the string
 #  sorted by the length of the word.
-# Time complexity: ?
-# Space complexity: ?
+# Time complexity: O(n^2)
+# Space complexity: O(n)
 def sort_by_length(my_sentence)
-  raise NotImplementedError, "Method not implemented"
-end
+  return nil if my_sentence.nil?
+  
+  my_sorted_array = []
+  my_array = my_sentence.split
+  
+  until my_array.length == 0 do
+    current_word = my_array[0]
+    my_array.each do |word|
+      if word.length  < current_word.length
+        current_word = word
+      end
+    end
+    my_sorted_array.push(current_word)
+    my_array.delete(current_word)
+  end
+  return my_sorted_array
+end
\ No newline at end of file
diff --git a/test/sort_by_length.rb b/test/sort_by_length_test.rb
similarity index 100%
rename from test/sort_by_length.rb
rename to test/sort_by_length_test.rb