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author | William Carroll <wpcarro@gmail.com> | 2020-01-29T14·43+0000 |
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committer | William Carroll <wpcarro@gmail.com> | 2020-01-29T14·43+0000 |
commit | 5c9079a41059e077f2b71b68eb83ff9fcb2e38d1 (patch) | |
tree | dce7e3566b04213228fb3c92fc593ca18841d972 /data_structures_and_algorithms/delete-node.py | |
parent | fb9380ba268b3cd27372acadb87b14cc96163374 (diff) |
Splice ./universe directory into ./
Manually merging: - README.md: I added the description from universe/README.md into the heading of dotfiles/README.md. - .envrc: dotfiles/.envrc was a superset of universe/.envrc - .gitignore: Adding some of the ignored patterns from universe/.gitignore to dotfiles/.gitignore Everything else here should be a simple rename.
Diffstat (limited to 'data_structures_and_algorithms/delete-node.py')
-rw-r--r-- | data_structures_and_algorithms/delete-node.py | 60 |
1 files changed, 60 insertions, 0 deletions
diff --git a/data_structures_and_algorithms/delete-node.py b/data_structures_and_algorithms/delete-node.py new file mode 100644 index 000000000000..7e431e224962 --- /dev/null +++ b/data_structures_and_algorithms/delete-node.py @@ -0,0 +1,60 @@ +import unittest + + +################################################################################ +# Solution +################################################################################ +def delete_node(x): + if not x.next: + raise Exception('Cannot delete the last node in a linked list.') + else: + x.value = x.next.value + x.next = x.next.next + + +################################################################################ +# 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 setUp(self): + self.fourth = Test.LinkedListNode(4) + self.third = Test.LinkedListNode(3, self.fourth) + self.second = Test.LinkedListNode(2, self.third) + self.first = Test.LinkedListNode(1, self.second) + + def test_node_at_beginning(self): + delete_node(self.first) + actual = self.first.get_values() + expected = [2, 3, 4] + self.assertEqual(actual, expected) + + def test_node_in_middle(self): + delete_node(self.second) + actual = self.first.get_values() + expected = [1, 3, 4] + self.assertEqual(actual, expected) + + def test_node_at_end(self): + with self.assertRaises(Exception): + delete_node(self.fourth) + + def test_one_node_in_list(self): + unique = Test.LinkedListNode(1) + with self.assertRaises(Exception): + delete_node(unique) + + +unittest.main(verbosity=2) |