class MyQueue(object):
def __init__(self, ):
"""
Initialize your data structure here.
"""
self.instack = []
self.outstack = []
def push(self, x):
"""
Push element x to the back of queue.
:type x: int
:rtype: void
"""
self.instack.append(x)
def pop(self):
"""
Removes the element from in front of queue and returns that element.
:rtype: int
"""
if not self.outstack:
if not self.instack:
return
else:
while self.instack:
node = self.instack.pop()
self.outstack.append(node)
return self.outstack.pop()
def peek(self):
"""
Get the front element.
:rtype: int
"""
if not self.outstack:
if not self.instack:
return
else:
while self.instack:
node = self.instack.pop()
self.outstack.append(node)
return self.outstack[-1]
def empty(self):
"""
Returns whether the queue is empty.
:rtype: bool
"""
if len(self.instack) == 0 and len(self.outstack) == 0:
return True
else:
return False
# Your MyQueue object will be instantiated and called as such:
# obj = MyQueue()
# obj.push(x)
# param_2 = obj.pop()
# param_3 = obj.peek()
# param_4 = obj.empty()
