binary-tree-upside-down.py

"""
Definition of TreeNode:
class TreeNode:
    def __init__(self, val):
        self.val = val
        self.left, self.right = None, None
"""

class Solution:
    """
    @param root: the root of binary tree
    @return: new root
    """
    def upsideDownBinaryTree(self, root):
        # write your code here
        # 递归版本，非递归待版本TODO。
        if (root == None) or (root.left == None):
            return root
        _root = self.upsideDownBinaryTree(root.left)
        root.left.left = root.right
        root.left.right = root
        root.left = None
        root.right = None
        return _root

# medium: https://www.lintcode.com/problem/binary-tree-upside-down