message: Update clone-binary-tree-with-random-pointer.py
diff: @@ -96,13 +96,16 @@ class Solution_Recu(object):
  # Time: O(n)
  # Space: O(n)
  +import collections
  +
  +
  class Solution2(object):
  def copyRandomBinaryTree(self, root):
  """
  :type root: Node
  :rtype: NodeCopy
  """
  - lookup = defaultdict(lambda: NodeCopy())
  + lookup = collections.defaultdict(lambda: NodeCopy())
  lookup[None] = None
  stk = [root]
  while stk:
  @@ -120,6 +123,9 @@ class Solution2(object):
  # Time: O(n)
  # Space: O(n)
  +import collections
  +
  +
  class Solution2_Recu(object):
  def copyRandomBinaryTree(self, root):
  """
  @@ -136,7 +142,7 @@ class Solution2_Recu(object):
  dfs(node.left, lookup)
  dfs(node.right, lookup)
  - lookup = defaultdict(lambda: NodeCopy())
  + lookup = collections.defaultdict(lambda: NodeCopy())
  lookup[None] = None
  dfs(root, lookup)
  return lookup[root]
  