用两个栈实现队列
# -*- coding:utf-8 -*-
class Solution:
def __init__(self):
self.stackA=[]
self.stackB=[]
def push(self,node):
# write code here
self.stackA.append(node)
def pop(self):
# return xx
if self.stackB:
return self.stackB.pop()
elif not self.stackA:
return None
else:
while self.stackA:
self.stackB.append(self.stackA.pop())
return self.stackB.pop()
用连个队列实现栈
# -*- coding:utf-8 -*-
class Solution:
def __init__(self):
self.queueA=[]
self.queueB=[]
def push(self,node):
# write code here
if self.queueB:
self.queueB.append(node)
else:
self.queueA.append(node)
def pop(self):
# return xx
if self.queueB:
i = 1
length = len(self.queueB)
while self.queueB and i < length :
self.queueA.append(self.queueB.pop(0))
i += 1
return self.queueB.pop(0)
elif self.queueA :
i=1
length=len(self.queueA)
while self.queueA and i self.queueB.append(self.queueA.pop(0)) i+=1 return self.queueA.pop(0) else: return None