subtree(users/wpcarro): docking briefcase at '24f5a642'

git-subtree-dir: users/wpcarro
git-subtree-mainline: 464bbcb15c
git-subtree-split: 24f5a642af
Change-Id: I6105b3762b79126b3488359c95978cadb3efa789

users/wpcarro/scratch/deepmind/part_two/reverse-words.py

@@ -0,0 +1,74 @@
+import unittest
+
+
+def reverse(xs, i, j):
+    """Reverse array of characters, xs, in-place."""
+    while i < j:
+        xs[i], xs[j] = xs[j], xs[i]
+        i += 1
+        j -= 1
+
+
+def reverse_words(xs):
+    punctuation = None
+    if len(xs) > 0 and xs[-1] in ".?!":
+        punctuation = xs.pop()
+    reverse(xs, 0, len(xs) - 1)
+    i = 0
+    j = i
+    while j < len(xs):
+        while j < len(xs) and xs[j] != ' ':
+            j += 1
+        reverse(xs, i, j - 1)
+        j += 1
+        i = j
+    if punctuation:
+        xs.append(punctuation)
+
+
+# Tests
+class Test(unittest.TestCase):
+    def test_one_word(self):
+        message = list('vault')
+        reverse_words(message)
+        expected = list('vault')
+        self.assertEqual(message, expected)
+
+    def test_two_words(self):
+        message = list('thief cake')
+        reverse_words(message)
+        expected = list('cake thief')
+        self.assertEqual(message, expected)
+
+    def test_three_words(self):
+        message = list('one another get')
+        reverse_words(message)
+        expected = list('get another one')
+        self.assertEqual(message, expected)
+
+    def test_multiple_words_same_length(self):
+        message = list('rat the ate cat the')
+        reverse_words(message)
+        expected = list('the cat ate the rat')
+        self.assertEqual(message, expected)
+
+    def test_multiple_words_different_lengths(self):
+        message = list('yummy is cake bundt chocolate')
+        reverse_words(message)
+        expected = list('chocolate bundt cake is yummy')
+        self.assertEqual(message, expected)
+
+    def test_empty_string(self):
+        message = list('')
+        reverse_words(message)
+        expected = list('')
+        self.assertEqual(message, expected)
+
+    def test_bonus_support_punctuation(self):
+        message = list('yummy is cake bundt chocolate this!')
+        reverse_words(message)
+        expected = list('this chocolate bundt cake is yummy!')
+        self.assertEqual(message, expected)
+
+
+unittest.main(verbosity=2)