标签：put ret += key 中序 nod tput nal root
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
思路：中序遍历；然后关键点在于用了一个全局变量；
1 /** 2 * Definition for a binary tree node. 3 * public class TreeNode { 4 * int val; 5 * TreeNode left; 6 * TreeNode right; 7 * TreeNode(int x) { val = x; } 8 * } 9 */ 10 class Solution{ 11 private int sum = 0; 12 public TreeNode convertBST(TreeNode root) { 13 helper(root); 14 return root; 15 } 16 public void helper(TreeNode root){ 17 if (root!=null){ 18 helper(root.right); 19 root.val+=sum; 20 sum = root.val; 21 helper(root.left); 22 } 23 } 24 }
Add to List 538. Convert BST to Greater Tree
标签：put ret += key 中序 nod tput nal root
原文地址：http://www.cnblogs.com/David-Lin/p/7700156.html
