<h3><a title="题目描述" href="https://leetcode-cn.com/problems/convert-bst-to-greater-tree/">题目描述</a></h3>  <h4>方法一</h4> <pre class="EnlighterJSRAW" data-enlighter-language="python">class Solution(object): def convertBST(self, root): """ :type root: TreeNode :rtype: TreeNode """ ##反向中序遍历 然后把前面的值一直累加到当前节点值 stack = [] node = root val = 0 while stack or node: if node: stack.append(node) node = node.right else: node = stack.pop() val += node.val node.val = val node = node.left return root </pre> <p> </p> ## 思路 - v0版本 2遍DFS但是没有利用到BST的条件 - v1版本 反向中序遍历，记录在当前节点值之前的所有节点值之和 并加到当前节点值上即可 ```python ###反向中序遍历 stack,node = [],root while node or stack: if node: stack.append(node) node = node.right ##正向时为访问左节点 else: node = stack.pop() print(node.val) node = node.left ## 正向时为访问右节点 ```