Raisah V

lib/reverse_sentence.rb

@@ -1,6 +1,65 @@
 # A method to reverse the words in a sentence, in place.
-# Time complexity: ?
-# Space complexity: ?
+# Time complexity: The time complexity of this method is O(nm) where n is the length of my_sentence and m is the length of a word in my_sentence. The first while loop has a time complexity of O(1/2n) where n is the length of my_sentence. The second while loop has a time complexity of O(n)where n is the length of my_sentence and a nested while loop with a time complexity of (1/2m) where m is the length of the word within the sentence. So the total time complexity is O(3/2n * 1/2m) or O(nm).
+
+# Space complexity: The space complexity of this method is O(1) because the space that the variables take up stays constant regardless of the lengthe of the string.
+
 def reverse_sentence(my_sentence)
-  raise NotImplementedError
+
+  return nil if my_sentence == nil
+
+  # reverses all characters in sentence
+  i = 0
+  j = my_sentence.length - 1
+
+  while i < my_sentence.length / 2
+    temp_i = my_sentence[i]
+    temp_j = my_sentence[j]
+
+    my_sentence[i] = temp_j
+    my_sentence[j] = temp_i
+
+    i += 1 
+    j -= 1
+  end
+
+
+  # reverses any words in the sentence
+  i = 0
+  word_start = 0
+  word_end = 0
+  in_word = true
+
+  while i < my_sentence.length
+    if ( my_sentence[i] == " " || i == my_sentence.length - 1 ) && in_word == true
+
+      word_end = i 
+      word_end -= 1 if my_sentence[i] == " "
+
+      word_length = word_end - word_start + 1
+      count = 0
+
+      while count < word_length / 2
+        temp_start = my_sentence[word_start]
+        temp_end = my_sentence[word_end]
+
+        my_sentence[word_start] = temp_end
+        my_sentence[word_end] = temp_start
+
+        word_start += 1
+        word_end -= 1
+        count += 1
+      end
+
+      in_word = false
+    end
+
+    if my_sentence[i] != " " && in_word == false
+      word_start = i
+      in_word = true
+    end
+
+    i += 1
+  end
+
+  return my_sentence
 end

lib/sort_by_length.rb

@@ -1,7 +1,31 @@
 # 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: The time complexity of this method is O(n) where n is the length of the my_sentence_array, or the number of words in the my_sentence string. The time that the algorithm takes will increase linearly with the number of words passed in. 
+
+# Space complexity: The space complexity of this method is O(1) because the space that the variables take up stays constant regardless of how many words the string contains.
+
 def sort_by_length(my_sentence)
-  raise NotImplementedError, "Method not implemented"
+  my_sentence_array = my_sentence.split(" ")
+
+  i = 1
+
+  while i < my_sentence_array.length
+    comparison_index = i
+    j = i - 1
+
+    i.times do
+      if my_sentence_array[comparison_index].length < my_sentence_array[j].length
+        new_comparison_index = my_sentence_array[j]
+        new_j = my_sentence_array[comparison_index]
+
+        my_sentence_array[comparison_index] = new_comparison_index
+        my_sentence_array[j] = new_j
+      end
+      j -= 1
+      comparison_index -= 1
+    end
+    i += 1
+  end
+
+  return my_sentence_array
 end