def path_to(self, v):
if not self.has_path_to(v):
return None
path = Stack()
e = self.edge_to[v]
while e is not None:
path.push(e)
e = self.edge_to[e.fr]
return path
def topological_sort(graph):
visited = [False] * graph.num_vertices
stack = Stack()
for v in range(graph.num_vertices):
if visited[v]:
continue
depth_first_search(graph, v, visited, stack)
return stack
def path_to(self, v):
if not self.has_path_to(v):
return None
path = Stack()
while v != self.source:
path.push(v)
v = self.edge_to[v]
path.push(self.source)
return path
def is_balanced(seq):
stack = Stack()
brackets = {"(": ")", "[": "]", "{": "}"}
for idx, char in enumerate(seq):
if char in brackets.keys():
stack.push((char, idx + 1))
elif char in brackets.values():
if stack.empty():
return (False, idx + 1)
top, _ = stack.pop()
if brackets[top] != char:
return (False, idx + 1)
else:
continue
return (stack.empty(), len(seq) - 1 if not stack.top() else stack.pop()[1])
def test_peek_empty_stack(self):
newStack = Stack()
self.assertEqual(newStack.peek(), None)
def test_clear(self):
newStack = Stack([1,2,3,4,5])
newStack.clear()
self.assertEqual(newStack.size(), 0)
def test_pop_from_empty_stack(self):
newStack = Stack()
popped = newStack.pop()
self.assertEqual(popped, None)
def test_peek(self):
newStack = Stack([1,2,3,4])
self.assertEqual(newStack.peek(), 4)
def test_pop(self):
newStack = Stack([1,2,3,4])
popped = newStack.pop()
self.assertEqual(popped, 4)
self.assertEqual(newStack.size(), 3)
def test_push(self):
newStack = Stack()
newStack.push(1)
self.assertEqual(newStack.size(), 1)
def test_is_empty(self):
newStack = Stack()
self.assertTrue(newStack.is_empty())
def test_size(self):
newStack = Stack()
self.assertFalse(newStack.size())
def test_initialize_empty_stack(self):
try:
newStack = Stack()
print("test_initialize_empty_stack: PASS")
except:
print("test_initialize_empty_stack: FAIL")