def test_peek_checks_first_entry(self):
q = Queue()
q.enqueue(1)
q.enqueue(2)
self.assertEqual(1, q.peek())
def test_pop_empty_queue(self):
q = Queue()
try:
q.dequeue()
self.fail("Should not be able to dequeue empty queue")
except IndexError as e:
self.assertEqual("Queue is empty", str(e))
def test_push_pop_changes_size(self):
q = Queue()
self.assertEqual(0, len(q))
q.enqueue(1)
self.assertEqual(1, len(q))
q.enqueue(2)
self.assertEqual(2, len(q))
q.dequeue()
self.assertEqual(1, len(q))
q.dequeue()
self.assertEqual(0, len(q))
def visit_nodes():
work_list = Queue()
work_list.enqueue(from_vertice)
visited = set()
while work_list:
current_vertice = work_list.dequeue()
if current_vertice == to_vertice:
break
visited.add(current_vertice)
for neighbor in graph.neighbors(current_vertice):
if neighbor not in visited:
work_list.enqueue(neighbor)
parent[neighbor] = current_vertice
def nodes_at_level(graph, root, depth):
"""Returns the name of all vertices that are at the specified level.
If no such nodes exist, return an empty list.
Args:
graph(Graph): the graph to extract nodes from
root(str): the name of the root node to start from
depth(int): the depth away from the root node
Returns:
list(str): a list of the names of all vertices reachable at depth
Raises:
ValueError: if the depth is negative
ValueError: if root does not exist in the graph"""
if not graph.contains_vertice(root):
raise ValueError("Root not found in graph")
if depth < 0:
raise ValueError("Given invalid depth")
result = []
work_list = Queue()
work_list.enqueue((root, 0))
discovered = set()
while work_list:
current_vertice, current_level = work_list.dequeue()
if current_vertice in discovered:
continue
discovered.add(current_vertice)
if current_level < depth:
for neighbor in graph.neighbors(current_vertice):
work_list.enqueue((neighbor, current_level + 1))
elif current_level == depth:
result.append(current_vertice)
# neighbors at this point are discarded if level >= depth
return result
def test_empty_queue_length_and_bool(self):
q = Queue()
self.assertEqual(0, len(q))
self.assertFalse(q)
def test_push_peek(self):
q = Queue()
q.enqueue(10)
self.assertEqual(1, len(q))
self.assertEqual(10, q.peek())
def test_push_peek_pop_ordering(self):
q = Queue()
q.enqueue(1)
q.enqueue(2)
q.enqueue(3)
self.assertEqual(1, q.peek())
self.assertEqual(1, q.dequeue())
self.assertEqual(2, q.peek())
self.assertEqual(2, q.dequeue())
self.assertEqual(3, q.peek())
self.assertEqual(3, q.dequeue())