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| // @Title: 把二叉搜索树转换为累加树 (Convert BST to Greater Tree)
// @Author: 15816537946@163.com
// @Date: 2019-11-25 20:32:41
// @Runtime: 16 ms
// @Memory: 6.4 MB
/*
* @lc app=leetcode.cn id=538 lang=golang
*
* [538] 把二叉搜索树转换为累加树
*
* https://leetcode-cn.com/problems/convert-bst-to-greater-tree/description/
*
* algorithms
* Easy (56.65%)
* Likes: 147
* Dislikes: 0
* Total Accepted: 8.4K
* Total Submissions: 14.8K
* Testcase Example: '[5,2,13]'
*
* 给定一个二叉搜索树(Binary Search Tree),把它转换成为累加树(Greater
* Tree),使得每个节点的值是原来的节点值加上所有大于它的节点值之和。
*
* 例如:
*
*
* 输入: 二叉搜索树:
* 5
* / \
* 2 13
*
* 输出: 转换为累加树:
* 18
* / \
* 20 13
*
*
*/
/**
* Definition for a binary tree node.
* type TreeNode struct {
* Val int
* Left *TreeNode
* Right *TreeNode
* }
*/
func convertBST(root *TreeNode) *TreeNode {
var sum = 0
var travel func(root *TreeNode)
travel = func(root *TreeNode) {
if root == nil {
return
}
travel(root.Right)
sum += root.Val
root.Val = sum
travel(root.Left)
return
}
travel(root )
return root
}
|