def balancedSymbols(s):
stack = Stack()
for ch in s:
if ch in "({[":
stack.push(ch)
elif ch in ")}]":
if stack.is_empty() or not matching(stack.top(), ch):
return False
stack.pop()
# ignore all other characters
return stack.is_empty()
def reverse(s):
S = Stack()
for ch in s:
S.push(ch)
while not S.is_empty():
ch = S.pop()
print(ch, end="")
print()
class StackPushTestCase(unittest.TestCase):
def setUp(self):
self.stack = Stack()
def test_push_should_add_item_to_the_end_of_items_list(self):
self.stack.push(1)
self.assertEqual(self.stack.items.head.value, 1)
self.stack.push(2)
self.assertEqual(self.stack.items.head.next.value, 2)
def test_push_should_increment_stack_size(self):
self.stack.push(1)
self.assertEqual(self.stack.size(), 1)
def setUp(self):
self.stack = Stack()
class StackSizeTestCase(unittest.TestCase):
def setUp(self):
self.stack = Stack()
def test_size_should_return_the_number_of_items_in_the_stack(self):
self.assertEqual(self.stack.size(), 0)
self.stack.push(1)
self.assertEqual(self.stack.size(), 1)
self.stack.push(2)
self.assertEqual(self.stack.size(), 2)
self.stack.pop()
self.assertEqual(self.stack.size(), 1)
self.stack.peek()
self.assertEqual(self.stack.size(), 1)
def setUp(self):
self.stack = Stack()
self.stack.push(1)
self.stack.push(2)
self.stack.push(3)
class StackPeekTestCase(unittest.TestCase):
def setUp(self):
self.stack = Stack()
self.stack.push(1)
self.stack.push(2)
self.stack.push(3)
def test_peek_should_return_the_last_item_of_its_items_list(self):
self.assertEqual(self.stack.peek(), 3)
self.assertEqual(self.stack.peek(), 3)
self.assertEqual(self.stack.peek(), 3)
def test_peek_should_return_none_if_stack_is_already_empty(self):
self.stack.pop()
self.stack.pop()
self.stack.pop()
self.assertEqual(self.stack.peek(), None)
def test_peek_should_not_decrement_stack_size(self):
self.stack.peek()
self.assertEqual(self.stack.size(), 3)