diff --git a/lib/reverse_sentence.rb b/lib/reverse_sentence.rb
index 3fe7cac..c08241c 100644
--- a/lib/reverse_sentence.rb
+++ b/lib/reverse_sentence.rb
@@ -1,6 +1,41 @@
 # A method to reverse the words in a sentence, in place.
-# Time complexity: ?
-# Space complexity: ?
+# Time complexity: O(n^2), n == length of my_sentence string
+# Space complexity: O(1)
 def reverse_sentence(my_sentence)
-  raise NotImplementedError
-end
+  if my_sentence == "" || my_sentence == nil 
+    return my_sentence 
+  end 
+  a = 0
+  max_index = my_sentence.length - 1
+  b = max_index 
+  while a < b do 
+    temp = my_sentence[a] 
+    my_sentence[a] = my_sentence[b]
+    my_sentence[b] = temp
+    a += 1
+    b -=1
+  end 
+  i = 0
+  while i < max_index do  
+    if my_sentence[i] == " " 
+      i += 1
+    else 
+      j = i + 1
+      while j <= max_index && my_sentence[j] != " " do 
+        j += 1
+      end 
+      word_end_index = j
+      j -= 1
+      while i < j do 
+        temp_i = my_sentence[i]
+        my_sentence[i] = my_sentence[j]
+        my_sentence[j] = temp_i
+        i += 1
+        j -= 1
+      end 
+      i = word_end_index
+    end 
+  end 
+  return my_sentence  
+end  
+
diff --git a/lib/sort_by_length.rb b/lib/sort_by_length.rb
index a5713ad..044ec82 100644
--- a/lib/sort_by_length.rb
+++ b/lib/sort_by_length.rb
@@ -1,7 +1,26 @@
 # 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), n == number of words in the sentence
+# Space complexity: 1
 def sort_by_length(my_sentence)
-  raise NotImplementedError, "Method not implemented"
+  sentence_array = my_sentence.split
+  length = sentence_array.length 
+  (0...(length - 1)).each do |i|
+    min_index = i
+    j = i + 1
+    while j < length
+      if sentence_array[j].length < sentence_array[min_index].length
+        min_index = j
+      end
+      j += 1
+    end
+    if min_index != i
+      temp = sentence_array[min_index]
+      sentence_array[min_index] = sentence_array[i]
+      sentence_array[i] = temp
+    end
+    i += 1
+  end
+  return sentence_array
 end
+
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