def MirroRecursively(root): # root is None or just one node, return root if None == root or None == root.left and None == root.right: return root root.left, root.right = root.right, root.left MirroRecursively(root.left) MirroRecursively(root.right) return root
原文：http://www.cnblogs.com/yangykaifa/p/6940602.html