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author | William Carroll <wpcarro@gmail.com> | 2020-01-29T14·29+0000 |
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committer | William Carroll <wpcarro@gmail.com> | 2020-01-29T14·29+0000 |
commit | fb9380ba268b3cd27372acadb87b14cc96163374 (patch) | |
tree | f65d7fc8d8726499165a0949af39afd1abc8118c /universe/deepmind/reverse-linked-list.py | |
parent | 15110e6de9f85537c7847267caa35fa068aea001 (diff) | |
parent | 8ad51b24dd8719840aac47134835ea25cfe1b0b8 (diff) |
Add 'universe/' from commit '8ad51b24dd8719840aac47134835ea25cfe1b0b8'
git-subtree-dir: universe git-subtree-mainline: 15110e6de9f85537c7847267caa35fa068aea001 git-subtree-split: 8ad51b24dd8719840aac47134835ea25cfe1b0b8
Diffstat (limited to 'universe/deepmind/reverse-linked-list.py')
-rw-r--r-- | universe/deepmind/reverse-linked-list.py | 74 |
1 files changed, 74 insertions, 0 deletions
diff --git a/universe/deepmind/reverse-linked-list.py b/universe/deepmind/reverse-linked-list.py new file mode 100644 index 000000000000..82fac171d5d1 --- /dev/null +++ b/universe/deepmind/reverse-linked-list.py @@ -0,0 +1,74 @@ +import unittest + + +def reverse(node): + prev = None + next = None + curr = node + + while curr: + next = curr.next + curr.next = prev + prev = curr + curr = next + + return prev + + +# Tests +class Test(unittest.TestCase): + class LinkedListNode(object): + def __init__(self, value, next=None): + self.value = value + self.next = next + + def get_values(self): + node = self + values = [] + while node is not None: + values.append(node.value) + node = node.next + return values + + def test_short_linked_list(self): + second = Test.LinkedListNode(2) + first = Test.LinkedListNode(1, second) + + result = reverse(first) + self.assertIsNotNone(result) + + actual = result.get_values() + expected = [2, 1] + self.assertEqual(actual, expected) + + def test_long_linked_list(self): + sixth = Test.LinkedListNode(6) + fifth = Test.LinkedListNode(5, sixth) + fourth = Test.LinkedListNode(4, fifth) + third = Test.LinkedListNode(3, fourth) + second = Test.LinkedListNode(2, third) + first = Test.LinkedListNode(1, second) + + result = reverse(first) + self.assertIsNotNone(result) + + actual = result.get_values() + expected = [6, 5, 4, 3, 2, 1] + self.assertEqual(actual, expected) + + def test_one_element_linked_list(self): + first = Test.LinkedListNode(1) + + result = reverse(first) + self.assertIsNotNone(result) + + actual = result.get_values() + expected = [1] + self.assertEqual(actual, expected) + + def test_empty_linked_list(self): + result = reverse(None) + self.assertIsNone(result) + + +unittest.main(verbosity=2) |