class Queue:
def __init__(self):
self.size = 0
self.storage = SinglyLinkedList()
def __len__(self):
# returns the length of the queue
return self.size
def enqueue(self, value):
# increase the size of the queue by one
self.size += 1
# add the new value to the tail of our list
self.storage.add_to_tail(value)
def dequeue(self):
# return 0 if nothing is in the queue
if self.size == 0:
return None
# decrement the size of the queue by one
self.size -= 1
# remove the value from the head of our list and return the value of the
# removed head
value = self.storage.remove_head()
return value
def test_get_max(self):
"""
Tests that the maximum value in the list is
returned.
"""
sll = SinglyLinkedList()
sll.add_to_head(3)
sll.add_to_tail(9)
sll.add_to_head(10)
sll.add_to_head(4)
max_val = sll.get_max()
self.assertEqual(max_val, 10)
def test_add_to_tail(self):
"""
Tests that a new Node has been added to
the tail of the list.
"""
def get_tail_val(list):
currentNode = list.head
while currentNode.next:
currentNode = currentNode.next
return currentNode.value
sll = SinglyLinkedList()
sll.add_to_tail(1)
sll.add_to_tail(2)
self.assertEqual(get_tail_val(sll), 2)
sll.add_to_tail(90)
self.assertEqual(get_tail_val(sll), 90)
self.assertEqual(len(sll), 3)
class Queue:
def __init__(self):
self.size = 0
# Why is our DLL a good choice to store our elements?
self.storage = SinglyLinkedList()
def enqueue(self, value):
self.storage.add_to_tail(value)
self.size += 1
# print(f"Enqueued successfully; queue size is now {self.size}")
def dequeue(self):
print(self.size, self.size > 0)
if self.size > 0:
self.size -= 1
return self.storage.remove_from_head()
return None
def len(self):
return self.size
class SinglyLinkedListTests(unittest.TestCase):
def setUp(self):
self.list = SinglyLinkedList()
def test_add_to_tail(self):
self.list.add_to_tail(1)
self.assertEqual(self.list.tail.value, 1)
self.assertEqual(self.list.head.value, 1)
self.list.add_to_tail(2)
self.assertEqual(self.list.tail.value, 2)
self.assertEqual(self.list.head.value, 1)
def test_contains(self):
self.list.add_to_tail(1)
self.list.add_to_tail(2)
self.list.add_to_tail(5)
self.list.add_to_tail(10)
self.assertTrue(self.list.contains(10))
self.assertTrue(self.list.contains(2))
self.assertFalse(self.list.contains(1000))
def test_remove_head(self):
self.list.add_to_tail(10)
self.list.add_to_tail(20)
self.assertEqual(self.list.remove_head(), 10)
self.assertFalse(self.list.contains(10))
self.assertEqual(self.list.remove_head(), 20)
self.assertFalse(self.list.contains(20))
self.list.add_to_tail(10)
self.assertEqual(self.list.remove_head(), 10)
self.assertIsNone(self.list.head)
self.assertIsNone(self.list.tail)
self.assertIsNone(self.list.remove_head())
def test_get_max(self):
self.assertIsNone(self.list.get_max())
self.list.add_to_tail(100)
self.assertEqual(self.list.get_max(), 100)
self.list.add_to_tail(55)
self.assertEqual(self.list.get_max(), 100)
self.list.add_to_tail(101)
self.assertEqual(self.list.get_max(), 101)
