二叉搜索树与双向链表

# -*- coding:utf-8 -*-
# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None
class Solution:
    def Convert(self, pRootOfTree):
        # write code here
        if not pRootOfTree:
            return None
        if not pRootOfTree.left and not pRootOfTree.right:
            return pRootOfTree
        # 处理左子树

        left_tree = pRootOfTree.left
        # 递归调用的时候不接受返回，子树处理完即可，只有到了最根节点才返回
        self.Convert(pRootOfTree.left)
        if left_tree:
            while left_tree.right:
                left_tree = left_tree.right
        # 将左子树最大节点连接到根节点
            left_tree.right,pRootOfTree.left = pRootOfTree,left_tree

        # 处理右子树

        right_tree =  pRootOfTree.right
        self.Convert(pRootOfTree.right)
        if right_tree:
            while right_tree.left:
                right_tree = right_tree.left
            right_tree.left,pRootOfTree.right = pRootOfTree,right_tree
        while pRootOfTree.left:
            pRootOfTree = pRootOfTree.left
        return pRootOfTree