# ---
# title: 938. Range Sum of BST
# id: problem938
# author: Tian Jun
# date: 2020-10-31
# difficulty: Easy
# categories: Tree, Depth-first Search, Recursion
# link: <https://leetcode.com/problems/range-sum-of-bst/description/>
# hidden: true
# ---
# 
# Given the `root` node of a binary search tree, return _the sum of values of
# all nodes with a value in the range`[low, high]`_.
# 
# 
# 
# **Example 1:**
# 
# ![](https://assets.leetcode.com/uploads/2020/11/05/bst1.jpg)
# 
#     
#     
#     Input: root = [10,5,15,3,7,null,18], low = 7, high = 15
#     Output: 32
#     
# 
# **Example 2:**
# 
# ![](https://assets.leetcode.com/uploads/2020/11/05/bst2.jpg)
# 
#     
#     
#     Input: root = [10,5,15,3,7,13,18,1,null,6], low = 6, high = 10
#     Output: 23
#     
# 
# 
# 
# **Constraints:**
# 
#   * The number of nodes in the tree is in the range `[1, 2 * 104]`.
#   * `1 <= Node.val <= 105`
#   * `1 <= low <= high <= 105`
#   * All `Node.val` are **unique**.
# 
# 
## @lc code=start
using LeetCode

## add your code here:
## @lc code=end
