message: add a solution
  * add a solution
  use a simple trick
  * Update binary-tree-zigzag-level-order-traversal.py
diff: @@ -14,7 +14,7 @@ class Solution(object):
  def zigzagLevelOrder(self, root):
  if root is None:
  return []
  - result, current, level = [], [root], 1
  + result, current = [], [root]
  while current:
  next_level, vals = [], []
  for node in current:
  @@ -23,11 +23,6 @@ class Solution(object):
  next_level.append(node.left)
  if node.right:
  next_level.append(node.right)
  - if level % 2:
  - result.append(vals)
  - else:
  - result.append(vals[::-1])
  - level += 1
  + result.append(vals[::-1] if len(result) % 2 else vals)
  current = next_level
  return result
  -
  