message: Update strobogrammatic-number-ii.py
diff: # Space: O(n)
  class Solution(object):
  + def findStrobogrammatic(self, n):
  + """
  + :type n: int
  + :rtype: List[str]
  + """
  lookup = {'0':'0', '1':'1', '6':'9', '8':'8', '9':'6'}
  + result = ['0', '1', '8'] if n%2 else ['']
  + for i in xrange(n%2, n, 2):
  + result = [a + num + b for a, b in lookup.iteritems() if i != n-2 or a != '0' for num in result]
  + return result
  - # @param {integer} n
  - # @return {string[]}
  - def findStrobogrammatic(self, n):
  - return self.findStrobogrammaticRecu(n, n)
  - def findStrobogrammaticRecu(self, n, k):
  +# Time: O(n * 5^(n/2))
  +# Space: O(n)
  +class Solution2(object):
  + def findStrobogrammatic(self, n):
  + """
  + :type n: int
  + :rtype: List[str]
  + """
  + lookup = {'0':'0', '1':'1', '6':'9', '8':'8', '9':'6'}
  + def findStrobogrammaticRecu(n, k):
  if k == 0:
  return ['']
  elif k == 1:
  return ['0', '1', '8']
  -
  result = []
  - for num in self.findStrobogrammaticRecu(n, k - 2):
  - for key, val in self.lookup.iteritems():
  + for num in findStrobogrammaticRecu(n, k - 2):
  + for key, val in lookup.iteritems():
  if n != k or key != '0':
  result.append(key + num + val)
  -
  return result
  + return findStrobogrammaticRecu(n, n)
  +
  