Tiffany C.

lib/reverse_sentence.rb

@@ -1,6 +1,30 @@
 # A method to reverse the words in a sentence, in place.
-# Time complexity: ?
-# Space complexity: ?
+# Time complexity: O(n^2)
+# Space complexity: O(1)
 def reverse_sentence(my_sentence)
-  raise NotImplementedError
+  return nil if my_sentence == nil
+
+  len = my_sentence.length
+
+  (len / 2).times do |i|
+    temp = my_sentence[len - i - 1]
+    my_sentence[len - i - 1] = my_sentence[i]
+    my_sentence[i] = temp
+  end
+
+  first_index = 0
+
+  len.times do |j|
+    if my_sentence[j + 1] == " " || j == len - 1
+      ((j - first_index + 1) / 2).times do |k|
+        temp = my_sentence[j - k]
+        my_sentence[j - k] = my_sentence[first_index + k]
+        my_sentence[first_index + k] = temp
+      end
+
+      first_index = j + 2
+    end
+  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: O(n^2)
+# Space complexity: O(1)
 def sort_by_length(my_sentence)
-  raise NotImplementedError, "Method not implemented"
+
+  # I'm assuming split is O(n), 
+  # can't imagine it needing more than one pass through n
+  sent_array = my_sentence.split(" ")
+  count = sent_array.length
+
+  if count == 0
+    return sent_array
+  end
+
+  i = 1
+  while i < count
+    to_insert = sent_array[i]
+    j = i
+
+    while j > 0 && sent_array[j-1].length > to_insert.length
+      sent_array[j] = sent_array[j-1]
+      j -= 1
+    end
+
+    sent_array[j] = to_insert
+    i += 1
+  end
+
+  return sent_array
 end

test/sort_by_length.rb → test/sort_by_length_test.rb

@@ -8,12 +8,12 @@
   it "will return an array of words, by length" do
     expect(sort_by_length("I love Ada")).must_equal ["I", "Ada", "love"]
   end
-
+  
   it "will return an array of words by length, words that are of equal length will appear in the order they appear" do
     expect(sort_by_length("words of equal length")).must_equal ["of", "words", "equal", "length"]
   end
-
+  
   it "will return an array of words by length, words that are of equal length will appear in the order they appear" do
     expect(sort_by_length("I love great awesome words")).must_equal ["I", "love", "great", "words", "awesome"]
   end
-end
+end