class Stack:
def __init__(self, length=5):
self.q1 = Queue(length)
self.q2 = Queue(length)
# O(1)
def push(self, x):
self.q1.enqueue(x)
# O£¨n£©
def pop(self):
if self.q1.isEmpty():
raise Exception("Empty Stack")
while len(self.q1) > 1:
self.q2.enqueue(self.q1.dequeue())
v = self.q1.dequeue()
self.q1, self.q2 = self.q2, self.q1
return v
# O(1)
def isEmpty(self):
return self.q1.isEmpty()
