def test_linked_list_with_no_cycle(self):
fourth = Test.LinkedListNode(4)
third = Test.LinkedListNode(3, fourth)
second = Test.LinkedListNode(2, third)
first = Test.LinkedListNode(1, second)
result = contains_cycle(first)
self.assertFalse(result)
def test_cycle_loops_to_beginning(self):
fourth = Test.LinkedListNode(4)
third = Test.LinkedListNode(3, fourth)
second = Test.LinkedListNode(2, third)
first = Test.LinkedListNode(1, second)
fourth.next = first
result = contains_cycle(first)
self.assertTrue(result)
def test_two_node_cycle_at_end(self):
fifth = Test.LinkedListNode(5)
fourth = Test.LinkedListNode(4, fifth)
third = Test.LinkedListNode(3, fourth)
second = Test.LinkedListNode(2, third)
first = Test.LinkedListNode(1, second)
fifth.next = fourth
result = contains_cycle(first)
self.assertTrue(result)
def test_cycle_loops_to_middle(self):
fifth = Test.LinkedListNode(5)
fourth = Test.LinkedListNode(4, fifth)
third = Test.LinkedListNode(3, fourth)
second = Test.LinkedListNode(2, third)
first = Test.LinkedListNode(1, second)
fifth.next = third
result = contains_cycle(first)
self.assertTrue(result)
def test_one_element_linked_list_cycle(self):
first = Test.LinkedListNode(1)
first.next = first
result = contains_cycle(first)
self.assertTrue(result)
def test_one_element_linked_list_no_cycle(self):
first = Test.LinkedListNode(1)
result = contains_cycle(first)
self.assertFalse(result)
def test_empty_list(self):
result = contains_cycle(None)
self.assertFalse(result)