tvl-depot/data_structures_and_algorithms/delete-node.py
William Carroll 5c9079a410 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.
2020-01-29 14:43:20 +00:00

60 lines
1.8 KiB
Python

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)