def test_7(self):
""" next of prior head is now head """
dl = DoubleLinkedList()
n1 = Node(5)
n2 = Node(3)
dl.push(n1)
dl.push(n2)
dl.pop()
self.assertEqual(dl.head._value, 5)
def test_6(self):
"""check that pop removes head"""
n1 = Node('A')
n2 = Node('B')
dl = DoubleLinkedList()
dl.append(n1) #head and tail at this point
dl.append(n2) # A is head and B is now tail
dl.pop() # removes A so head value should be B
self.assertEqual(dl.head._value, 'B')
def find_components(g: Graph):
"""
Breadth First Search Alg. Which also:
tests if the graph is connected,
computes the distance from s to the other edges
labels the vertices in the order they are visited
:param g: Graph
:return: (isConnected, {dict of components})
"""
visited = set()
components = dict()
count = 1
while len(visited) < len(g.vertices):
for o in g.vertices:
if o not in visited:
v = o
break
queue = DoubleLinkedList() # queue
queue.append(v)
visited.add(v)
components[count] = [v]
while len(queue) > 0:
w = queue.pop() # BFS so FIFO
for n in w.neighbours:
# If w not visited
if n not in visited:
visited.add(n)
queue.append(n)
components[count].append(n)
count += 1
is_connected = len(components) == 1
return is_connected, components
class Deque(object):
"""Class deque for deque composition."""
def __init__(self):
"""Init for deque."""
self._new_dll = DoubleLinkedList()
def append(self, val):
"""Enqueue function for queue pushes value to head."""
return self._new_dll.push(val)
def appendleft(self, val):
"""Append vals to the front of deque."""
return self._new_dll.append(val)
def pop(self):
"""Pop from dll."""
return self._new_dll.pop()
def popleft(self):
"""Shift for popleft."""
return self._new_dll.shift()
def peek(self): # pragma no cover
"""Return a new value without dequeuing it."""
print(self._new_dll.head.data)
def peekleft(self): # pragma no cover
"""Return a new value from the left without dequeing it."""
print(self._new_dll.tail.data)
def __len__(self):
"""Length function for the queue."""
return len(self._new_dll)
class Queue(object):
"""Will create a instance of Queue and allow enqueue(), dequeue(), peek(), size() and len() methods to work."""
def __init__(self, iterable=None):
"""Will init a new instance of the Stack class."""
from dll import DoubleLinkedList
self._dll = DoubleLinkedList()
self._counter = 0
def enqueue(self, data):
"""Will push a new element into the Queue."""
self._dll.append(data)
self._counter += 1
def dequeue(self):
"""Will remove the first element in the Queue."""
if self._dll.head:
self._counter -= 1
return self._dll.pop()
def peek(self):
"""Will return the next value in the Queue."""
return self._dll.head.data
def __len__(self):
"""Will return the length of the stack using len()."""
return self._counter
class Deque(object):
"""Will create a instance of Deque."""
def __init__(self, iterable=None):
"""Will init a new instance of the Stack class."""
from dll import DoubleLinkedList
self._dll = DoubleLinkedList()
self._counter = 0
def append(self, data):
"""Will push a new element into the Deque."""
self._dll.append(data)
self._counter += 1
def pop_left(self):
"""Will remove the head value."""
if self._dll.head:
self._counter -= 1
else:
raise ValueError('no value left to pop')
return self._dll.pop()
def append_left(self, data):
"""Append a value to the head."""
self._dll.push(data)
self._counter += 1
def pop(self):
"""Pop a value from the end."""
if self._dll.tail:
self._counter -= 1
else:
raise ValueError('no value left to pop')
return self._dll.shift()
def peek_left(self):
"""Will return the value that pop_left would return."""
if self._dll.head:
return self._dll.head.data
else:
raise ValueError('no value in the deque to peek')
def peek(self):
"""Will return the value that pop would return."""
if self._dll.head:
return self._dll.tail.data
else:
raise ValueError('no value in the deof correct typeque to peek')
def size(self):
"""Return the size of the deque."""
return self._counter
def __len__(self):
"""Will return the length of the deque using len()."""
return self._counter
class Deque(object):
"""Deque data structure, can add and remove from both ends."""
def __init__(self):
"""Initialize the deque."""
self.deque = DoubleLinkedList()
def append(self, value):
"""Add an item to the back of the deque."""
self.deque.append(value)
def append_left(self, value):
"""Add an item to the front of the deque."""
self.deque.push(value)
def pop(self):
"""Pop a value off of the back of the deque and return it."""
return self.deque.shift()
def pop_left(self):
"""Pop a value off of the front of the deque and return it."""
return self.deque.pop()
def peek(self):
"""Return the next value that would be poped at the end of deque."""
try:
return self.deque.tail.data
except AttributeError:
return None
def peek_left(self):
"""Return the next value to pop in the deque."""
try:
return self.deque.head.data
except AttributeError:
return None
def size(self):
"""Return the number of nodes in the deque."""
return self.deque.__len__()
class DoublyLinkedListCase(unittest.TestCase):
dll = None
def setUp(self):
self.dll = DoubleLinkedList()
def test_init(self):
self.assertIsNone(self.dll._head, "Initial HEAD should be None")
self.assertIsNone(self.dll._tail, "Initial TAIL should be None")
self.assertEqual(0, len(self.dll), "Initial length should be zero")
def test_append_left(self):
self.dll.append_left(1)
self.assertEqual(1, self.dll._head.value,
"Expected value 1 in first Node")
self.assertEqual(1, len(self.dll), "Length should be 1")
self.assertEqual(self.dll._head, self.dll._tail,
"HEAD should equal TAIL")
prev_added_node = self.dll._head
count = 1
for i in range(5):
self.dll.append_left(i)
count += 1
self.assertEqual(i, self.dll._head.value,
"Expected value " + str(i) + " in first Node")
self.assertEqual(
prev_added_node.value, self.dll._head.next.value,
"Expected value" + str(prev_added_node.value) + "in next Node")
self.assertEqual(count, len(self.dll),
"Length should be " + str(count))
self.assertEqual(prev_added_node, self.dll._head.next,
"First node should point to second node")
self.assertEqual(self.dll._head, prev_added_node.prev,
"Second node should point to this node")
prev_added_node = self.dll._head
def test_append(self):
self.dll.append(1)
self.assertEqual(self.dll._head.value, 1,
"Expected value 1 in first Node")
self.assertEqual(len(self.dll), 1, "Length should be 1")
self.assertEqual(self.dll._head, self.dll._tail,
"HEAD should equal TAIL")
prev_added_node = self.dll._tail
count = 1
for i in range(5):
self.dll.append(i)
count += 1
self.assertEqual(self.dll._tail.value, i,
"Expected value " + str(i) + " in last Node")
self.assertEqual(
self.dll._tail.prev.value, prev_added_node.value,
"Expected value" + str(prev_added_node.value) +
"in previous Node")
self.assertEqual(len(self.dll), count,
"Length should be " + str(count))
self.assertEqual(self.dll._tail.prev, prev_added_node,
"Added node should point to second last node")
self.assertEqual(prev_added_node.next, self.dll._tail,
"Second Last node should point to added node")
prev_added_node = self.dll._tail
def test_pop(self):
count = 5
for i in range(count):
self.dll.append(i)
self.assertEqual(count, len(self.dll),
"Length should be " + str(count))
# Pop from a dll with > 1 elements
for i in range(count, 1, -1):
value = self.dll.pop()
count -= 1
self.assertEqual(count, len(self.dll),
"Length should be " + str(count))
self.assertEqual(i - 1, value, "Value should equal " + str(i - 1))
self.assertIsNone(self.dll._tail.next, "TAIL.next should be None")
# Pop from a dll with 1 element
self.assertEqual(count, len(self.dll), "Length should be " + str(1))
value = self.dll.pop()
self.assertEqual(0, len(self.dll), "Length should be " + str(0))
self.assertEqual(0, value, "Value should equal " + str(0))
self.assertIsNone(self.dll._head, "HEAD should be None")
self.assertIsNone(self.dll._tail, "TAIL should be None")
# Pop from an empty dll
node = self.dll.pop()
self.assertIsNone(node, "Popping an empty dll returns None")
def test_pop_left(self):
n = count = 5
for i in range(count):
self.dll.append(i)
self.assertEqual(count, len(self.dll),
"Length should be " + str(count))
# Pop_left from a dll with > 1 elements
for i in range(count - 1):
value = self.dll.pop_left()
count -= 1
self.assertEqual(count, len(self.dll),
"Length should be " + str(count))
self.assertEqual(i, value, "Value should equal " + str(i))
self.assertEqual(i + 1, self.dll._head.value,
"Next value should equal " + str(i + 1))
# Pop from a dll with 1 element
self.assertEqual(count, len(self.dll), "Length should be " + str(1))
value = self.dll.pop_left()
self.assertEqual(0, len(self.dll), "Length should be " + str(0))
self.assertEqual(n - 1, value, "Value should equal " + str(n - 1))
self.assertIsNone(self.dll._head, "HEAD should be None")
self.assertIsNone(self.dll._tail, "TAIL should be None")
# Pop from an empty dll
node = self.dll.pop_left()
self.assertIsNone(node, "Popping an empty dll returns None")
def test_find(self):
n = 5
for i in range(n):
self.dll.append(i)
self.assertEqual(3, self.dll.find(3).value, "Can find value of 3")
self.assertIsNone(self.dll.find(10),
"Cannot find a node with a value of 10")
def test_insert_after(self):
n, m = 5, 3
for i in range(n):
self.dll.append(i)
node = self.dll.find(m)
node2 = node.next
self.dll.insert_after(node, 10)
self.assertEqual(10, node.next.value,
"Value of 10 is inserted after given node")
self.assertEqual(node.next, node2.prev,
"New node is inserted before 'node2")
expected = [i for i in range(n)]
expected.insert(m + 1, 10)
count = 0
for i in self.dll:
self.assertEqual(expected[count], i)
count += 1
# Insert after TAIL
self.dll.insert_after(self.dll._tail, 11)
self.assertEqual(11, self.dll._tail.value,
"Value of 11 is inserted at TAIL")
self.assertIsNone(self.dll._tail.next, "HEAD.next is None")
def test_insert_before(self):
n, m = 5, 3
for i in range(n):
self.dll.append(i)
node = self.dll.find(m)
node2 = node.prev
self.dll.insert_before(node, 10)
self.assertEqual(10, node.prev.value,
"Value of 10 is inserted before 'node'")
self.assertEqual(node2.next, node.prev,
"New node is inserted after 'node2")
expected = [i for i in range(n)]
expected.insert(m, 10)
count = 0
for i in self.dll:
self.assertEqual(expected[count], i)
count += 1
# Insert before HEAD
self.dll.insert_before(self.dll._head, 11)
self.assertEqual(11, self.dll._head.value,
"Value of 11 is inserted at HEAD")
self.assertIsNone(self.dll._head.prev, "HEAD.prev is None")
def test_remove(self):
n = 5
for i in range(n):
self.dll.append(i)
# Remove existing value
self.dll.remove(2)
self.assertEqual(n - 1, len(self.dll),
"Length should be " + str(n - 1))
self.assertIsNone(self.dll.find(2),
"There should be no value of 2 in the dll")
# print(self.dll)
# Remove non existing value
self.dll.remove(-1)
self.assertEqual(n - 1, len(self.dll),
"Length should still be" + str(n - 1))
def test_delete(self):
n = 5
for i in range(n):
self.dll.append(i)
# Delete existing value
node = self.dll.find(2)
prev = node.prev
next = node.next
val = self.dll.delete(node)
self.assertEqual(2, val, "Returned value should be 2")
self.assertEqual(n - 1, len(self.dll),
"Length should be " + str(n - 1))
self.assertIsNone(self.dll.find(2),
"There should be no value of 2 in the dll")
self.assertEqual(next, prev.next, "Links previous to next node")
self.assertEqual(prev, next.prev, "Links next node to previous")
# Delete non existing value
node = Node(2)
val = self.dll.delete(node)
self.assertIsNone(val, "Should return None")
self.assertEqual(n - 1, len(self.dll),
"Length should still be " + str(n - 1))
# print(self.dll)
# Delete first node
node = self.dll.find(0)
next = node.next
self.dll.delete(node)
self.assertEqual(len(self.dll), n - 2,
"Length should be " + str(n - 2))
self.assertIsNone(self.dll.find(0),
"There should be no value of 0 in the dll")
for elem in self.dll:
self.assertEqual(next.value, elem,
"Next should now be at the HEAD")
break
# print(self.dll)
# Delete last node
# print(self.dll)
# node = self.dll.find(n - 1)
def test_contains(self):
n = 5
for i in range(n):
self.dll.append(i)
# 0 - 4 should be contained in dll
for i in range(n):
self.assertTrue(i in self.dll, "DLL should contain " + str(i))
# Should not contain n
self.assertFalse(n in self.dll, "DLL should not contain" + str(n))