def test_length(self):
dq = LinkedDeque()
assert dq.length() == 0
dq.push_back('A')
assert dq.length() == 1
dq.push_back('B')
assert dq.length() == 2
dq.pop_front()
assert dq.length() == 1
dq.pop_front()
assert dq.length() == 0
def _traverse_level_order_iterative(self, start_node, visit):
"""Traverse this binary tree with iterative level-order traversal (BFS).
Start at the given node and visit each node with the given function.
Running time: O(n) all cases where n is the number of nodes and m is
the number of edges
Memory usage: O(?) where n is the number of nodes; best case where each
level stores only 1-2 nodes; worst case where all nodes are on the same
level except for the root node.
"""
# Create queue to store nodes not yet traversed in level-order
deque = LinkedDeque()
# Push given starting node
deque.push_back(start_node)
# Loop until deque is empty
while deque.length() > 0:
# Pop node at front of deque
node = deque.pop_front()
# Visit this node's data with given function
visit(node.data)
# Enqueue this node's left child, if it exists
if node.left:
deque.push_back(node.left)
# Enqueue this node's right child, if it exists
if node.right:
deque.push_back(node.right)
def test_pop_front(self):
dq = LinkedDeque(['A', 'B', 'C'])
assert dq.length() == 3
assert dq.front() == 'A'
dq.pop_front()
assert dq.length() == 2
assert dq.front() == 'B'
dq.pop_front()
assert dq.length() == 1
assert dq.front() == 'C'
assert dq.is_empty() == False
dq.pop_front()
assert dq.length() == 0
assert dq.front() == None
assert dq.is_empty() == True
def test_pop_front(self):
q = LinkedDeque()
with self.assertRaises(ValueError):
q.pop_front()
q.push_front("A")
assert q.length() == 1
assert q.pop_front() == "A"
assert q.is_empty() is True
q.push_front("one")
q.push_back("two")
assert q.pop_front() == "one"
assert q.pop_front() == "two"
with self.assertRaises(ValueError):
q.pop_front()
assert q.is_empty() is True