text: # Range Sum of BST
  
  '''
  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:
  
  
  Input: root = [10,5,15,3,7,null,18], low = 7, high = 15
  Output: 32
  Example 2:
  
  
  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.
  '''
  
  # Definition for a binary tree node.
  # class TreeNode:
  #     def __init__(self, val=0, left=None, right=None):
  #         self.val = val
  #         self.left = left
  #         self.right = right
  class Solution:
      def rangeSumBST(self, root: TreeNode, low: int, high: int) -> int:
          if not root:
              return 0
          if root.val>=low and root.val<=high:
              return root.val+self.rangeSumBST(root.left, low, high)+self.rangeSumBST(root.right, low, high)
          elif root.val>=low:
              return self.rangeSumBST(root.left, low, high)
          elif root.val<=high:
              return self.rangeSumBST(root.right, low, high)
          else:
              return 0
  