class TwoStackQueue:
def __init__(self):
self.enqueue_stack = Stack()
self.dequeue_stack = Stack()
def enqueue(self, item):
if self.enqueue_stack.isEmpty():
while not self.dequeue_stack.isEmpty():
self.enqueue_stack.push(self.dequeue_stack.pop())
self.enqueue_stack.push(item)
def dequeue(self):
if self.dequeue_stack.isEmpty():
if self.enqueue_stack.isEmpty():
IndexError
while not self.enqueue_stack.isEmpty():
self.dequeue_stack.push(self.enqueue_stack.pop())
return self.dequeue_stack.pop()
def peek(self):
if self.dequeue_stack.isEmpty():
if self.enqueue_stack.isEmpty():
IndexError
while not self.enqueue_stack.isEmpty():
self.dequeue_stack.push(self.enqueue_stack.pop())
return self.dequeue_stack.peek()
def isEmpty(self):
return self.enqueue_stack.isEmpty() and self.dequeue_stack.isEmpty()
def __len__(self):
return max(len(self.enqueue_stack), len(self.dequeue_stack))
def test_pop(self):
stack = Stack()
stack.push(1)
stack.push(2)
self.assertEqual(stack.pop(), 2)
stack.push(3)
self.assertEqual(stack.pop(), 3)
self.assertEqual(stack.pop(), 1)
stack.pop()
self.assertRaises(IndexError)
def parentheses_check(string):
parentheses = Stack()
pair = {'{': '}', '[': ']', '(': ')'}
for char in string:
if char in pair.keys():
parentheses.push(char)
elif char in pair.values():
if not parentheses.isEmpty() and char == pair[parentheses.peek()]:
parentheses.pop()
else:
return False
return parentheses.isEmpty()