LeetCode #938. Range Sum of BST 二叉搜索树的范围和

https://leetcode-cn.com/problems/range-sum-of-bst/

二叉树中序遍历

二叉搜索树性质：一个节点大于所有其左子树的节点，小于其所有右子树的节点

 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     public int rangeSumBST(TreeNode root, int L, int R) {
12         int result = 0;
13         
14         if (root != null) {
15             if (root.val >= L && root.val <= R) {
16                 result += root.val;
17             }
18             result += rangeSumBST(root.left, L, R);
19             result += rangeSumBST(root.right, L, R);
20         }
21         return result;
22     }
23 }