diff --git a/README.md b/README.md
index 76f4476..c14e48e 100644
--- a/README.md
+++ b/README.md
@@ -1,10 +1,14 @@
 # String Reverse
-In this assignment, you'll design and implement one of the string manipulation functions that is commonly asked during interviews.
-Remember that a string is an array of characters. Algorithms that worked on restricted arrays will work on strings as well.
+In this assignment, you'll design and implement one of the string manipulation functions.
+Remember that a string is an array of characters. Algorithms that worked on array data structure will work on strings as well.
 
 ## Exercise
-* Design and implement a method to reverse a string *in place*. For example, if the method is called with input parameter of "Lovelace", the method should update the input string object to have the value "ecalevoL".
-* Share and explain the time and space complexities for your solution.
-* At minimum, your implementation should pass the basic tests.
-
-**Note**: Do not use Ruby provided functionality for `.reverse` and `.reverse!`. You may use `.length`.
+* Design and implement a method to reverse a string *in place*. The method takes the string to be reversed as input parameter.
+* Above the method, elaborate the comment to share the time and space complexity of your method.
+    * Your solution should optimize the space complexity as much as possible. In other words, do not use any more space than needed.
+    * If you explain the complexity in terms of *n*, be sure to explain what *n* stands for.
+* For example, if the method is called with input parameter of "*Lovelace*", the method should update the input string object to have the value "*ecalevoL*".
+* <b>Notes</b>: 
+    * Do not use Ruby provided functionality for `.reverse` and `.reverse!`.
+    * You may use `.length` method available in the String class.
+    * You may access a character at a given index or set the value at a given index.
diff --git a/lib/string_reverse.rb b/lib/string_reverse.rb
index ad7dc0d..3b06ca5 100644
--- a/lib/string_reverse.rb
+++ b/lib/string_reverse.rb
@@ -1,4 +1,6 @@
 # A method to reverse a string in place.
+# Time complexity: ?
+# Space complexity: ?
 def string_reverse(my_string)
-  my_string << "not implemented"
+  raise NotImplementedError
 end