finished

.github/PULL_REQUEST_TEMPLATE

@@ -6,13 +6,13 @@ What is the time and space complexity for each method you implemented? Provide j
 
 |  Question 	|  Answer 	|
 |---	|---	|
-|  What is the time complexity of the string_reverse method? Provide justification.	|   	|
-|  What is the space complexity of the string_reverse method? Provide justification.	|   	|
-|  What is the time complexity of the reverse_words method? Provide justification.	|   	|
-|  What is the space complexity of the reverse_words method? Provide justification.	|   	|
-|  What is the time complexity of the reverse_sentence method? Provide justification.	|   	|
-|  What is the space complexity of the reverse_sentence method? Provide justification.	|   	|
-|  What is the time complexity of the palindrome_check method? Provide justification.	|   	|
-|  What is the space complexity of the palindrome_check method? Provide justification.	|   	|
+|  What is the time complexity of the string_reverse method? Provide justification.	|  The time complexity of the string_reverse method is O(n) because the method can take as long as the length of the string.	|
+|  What is the space complexity of the string_reverse method? Provide justification.	| The space complexity is O(1) because the space is constant.  For this method there are temporary variables first_letter, last_letter, first_position, and last_position.|
+|  What is the time complexity of the reverse_words method? Provide justification.	|  The time complexity of the reverse_words method is O(n) because the method goes through every letter in my_words and then applies the string_reverse method. 	|
+|  What is the space complexity of the reverse_words method? Provide justification.	| The space complexity is constant.  Although there are many variables being saved, they are in temporary variable spaces.  	|
+|  What is the time complexity of the reverse_sentence method? Provide justification.	|    The time complexity of the reverse sentence method is O(n^2) because the reverse words method and the string_reverse methods are called which are both O(n) time complexity. 	|
+|  What is the space complexity of the reverse_sentence method? Provide justification.	| The space complexity is constant.  There are only temporary variables saved.	|
+|  What is the time complexity of the palindrome_check method? Provide justification.	|  The time complexity is O(n/2) which translates to O(n).  It is O(n/2) because the method only has to iterate through half of the argument. 	|
+|  What is the space complexity of the palindrome_check method? Provide justification.	|  The space complexity of the palindrome check is constant.  There are no permanent variables saved.  	|
 |  What is the time complexity of the encode_repeating method? Provide justification.	|   	|
 |  What is the space complexity of the encode_repeating method? Provide justification.	|   	|

string_manipulation.rb

@@ -1,26 +1,79 @@
 # A method to reverse a string in place.
+require 'pry'
 def string_reverse(my_string)
-  puts "NOT IMPLEMENTED"
+
+  last_position = (my_string.length - 1)
+
+  first_position = 0
+
+  while last_position > first_position
+    first_letter = my_string[first_position]
+    last_letter = my_string[last_position]
+
+    my_string[first_position] = last_letter
+    my_string[last_position] = first_letter
+
+    last_position -= 1
+    first_position += 1
+  end
+
+  my_string
+
 end
 
 # A method to reverse each word in a sentence, in place.
 def reverse_words(my_words)
-  puts "NOT IMPLEMENTED"
+  first_position = 0
+  last_position = (my_words.length - 1)
+
+  word = ""
+  word_starting_index = 0
+  word_ending_index = 0
+  until first_position == last_position + 1
+    character = my_words[first_position]
+    if character == " "
+      my_words[word_starting_index .. word_ending_index] = string_reverse(word)
+      my_words[first_position] = character
+      word = ""
+      first_position += 1
+      word_starting_index = first_position
+    else
+      word += character
+      word_ending_index = first_position
+      first_position += 1
+    end
+  end
+  my_words[word_starting_index .. word_ending_index] = string_reverse(word)
 end
 
 # A method to reverse the words in a sentence, in place.
 def reverse_sentence(my_sentence)
-  puts "NOT IMPLEMENTED"
+  reverse_words(my_sentence)
+  string_reverse(my_sentence)
 end
 
-# A method to check if the input string is a palindrome.
-# Return true if the string is a palindrome. Return false otherwise.
+# A method to check if the input my_string is a palindrome.
+# Return true if the my_string is a palindrome. Return false otherwise.
 def palindrome_check(my_phrase)
-  puts "NOT IMPLEMENTED"
-  return true
+  string_fixed = my_phrase.split.join
+  first_position = 0
+  last_position = string_fixed.length - 1
+
+  while first_position != last_position
+
+    case
+    when string_fixed[first_position] != string_fixed[last_position]
+      return false
+      exit
+    when string_fixed[first_position] == string_fixed[last_position]
+      first_position += 1
+      last_position -= 1
+    end
+    return true
+  end
 end
 
-# A method that updates the string by replacing consecutive repeating characters
+# A method that updates the my_string by replacing consecutive repeating characters
 # with a number representing the frequency. The replacement is done only if the
 # string length will get reduced by the process.
 def encode_repeating(my_string)