LeetCode 538. Convert BST to Greater Tree

考点	难度
DFS	Medium

题目

Given the root of a Binary Search Tree (BST), convert it to a Greater Tree such that every key of the original BST is changed to the original key plus the sum of all keys greater than the original key in BST.

让客户满意是我们工作的目标，不断超越客户的期望值来自于我们对这个行业的热爱。我们立志把好的技术通过有效、简单的方式提供给客户，将通过不懈努力成为客户在信息化领域值得信任、有价值的长期合作伙伴，公司提供的服务项目有：国际域名空间、网站空间、营销软件、网站建设、宁国网站维护、网站推广。

As a reminder, a binary search tree is a tree that satisfies these constraints:

The left subtree of a node contains only nodes with keys less than the node’s key.
The right subtree of a node contains only nodes with keys greater than the node’s key.
Both the left and right subtrees must also be binary search trees.

思路

inverse traversal

答案

class Solution(object):
    def convertBST(self, root):
        self.val = 0
        def visit(root):
            if root:
                visit(root.right)
                root.val += self.val
                self.val = root.val
                visit(root.left)
        visit(root)
        return root

你是否还在寻找稳定的海外服务器提供商？创新互联www.cdcxhl.cn海外机房具备T级流量清洗系统配攻击溯源，准确流量调度确保服务器高可用性，企业级服务器适合批量采购，新人活动首月15元起，快前往官网查看详情吧

文章题目：LeetCode知识点总结-538-创新互联
本文网址：http://ybzwz.com/article/csicpi.html