Given 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 sum of all keys greater than the original key in BST.
Example:
Input: The root of a Binary Search Tree like this: 5 / 2 13 Output: The root of a Greater Tree like this: 18 / 20 13
# Definition for a binary tree node.# class TreeNode(object):# def __init__(self, x):# self.val = x# self.left = None# self.right = Noneclass Solution(object):def convertBST(self, root):""":type root: TreeNode:rtype: TreeNode"""self.helper(root)return rootsum = 0def helper(self, node):if(node):self.helper(node.right)node.val += self.sumself.sum = node.valself.helper(node.left)
538. Convert BST to Greater Tree 二叉搜索树转换为更大树
原文：http://www.cnblogs.com/xiejunzhao/p/7143630.html