题解 | #二叉搜索树与双向链表#

# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

#
# 
# @param pRootOfTree TreeNode类 
# @return TreeNode类
#
class Solution:
    def mid_DFS(self , pRootOfTree):
        global output
        if not pRootOfTree:
            return
        self.mid_DFS(pRootOfTree.left)
        output.right=pRootOfTree
        pRootOfTree.left=output
        output=pRootOfTree
        self.mid_DFS(pRootOfTree.right)

    
    def Convert(self , pRootOfTree ):
        # write code here
        if not pRootOfTree:
            return
        global output
        output=TreeNode(None)
        self.mid_DFS(pRootOfTree)
        while output.left.val!=None:
            output=output.left
        output.left=None
        return output