操作|实现方式  list  collections.deque
-----------------------------------------
addFront    O(n)  O(1)
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addRear     O(1)  O(1)
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removeFront   O(n)  O(1)
-----------------------------------------
removeRear   O(1)  O(1)

#!/usr/bin/env python
# -*- coding: utf-8 -*-
class Deque:
  def __init__(self):
    self.items = []
  def addFront(self, item):
    self.items.insert(0, item)
  def addRear(self, item):
    self.items.append(item)
  def removeFront(self):
    return self.items.pop(0)
  def removeRear(self):
    return self.items.pop()
  def empty(self):
    return self.size() == 0
  def size(self):
    return len(self.items)

#!/usr/bin/env python
# -*- coding: utf-8 -*-
from collections import deque
class Deque:
  def __init__(self):
    self.items = deque()
  def addFront(self, item):
    self.items.appendleft(item)
  def addRear(self, item):
    self.items.append(item)
  def removeFront(self):
    return self.items.popleft()
  def removeRear(self):
    return self.items.pop()
  def empty(self):
    return self.size() == 0
  def size(self):
    return len(self.items)

#!/usr/bin/env python
# -*- coding: utf-8 -*-
def palchecker(aString):
  chardeque = Deque()
  for ch in aString:
    chardeque.addRear(ch)
  while chardeque.size() > 1:
    first = chardeque.removeFront()
    last = chardeque.removeRear()
    if first != last:
      return False
  return True
if __name__ == '__main__':
  str1 = 'able was i ere i saw elba'
  print('"%s" is%s palindrome' % (str1, '' if palchecker(str1) else ' not'))
  str2 = u'人人为我、我为人人'
  print(u'"%s"%s是回文' % (str2, u'' if palchecker(str2) else u'不'))
  str3 = u"What's wrong 怎么啦"
  print(u'"%s"%s是回文' % (str3, u'' if palchecker(str3) else u'不'))

$ python palchecker.py
"able was i ere i saw elba" is palindrome
"人人为我、我为人人"是回文
"What's wrong 怎么啦"不是回文