Sum of BST Nodes Within Given Range

meta Given the root of a binary search tree and two integers low and high, return the sum of values of all nodes with a value in the inclusive range [low, high]. Input: root: The root node of the binary search tree low: An integer high: An integer Output: The sum of all node values within the range [low, high] Example: Input: root = [10,5,15,3,7,null,18], low = 7, high = 15 Output: 32 Constraints: The number of nodes in the tree is in the range [1, 2 * 10^4] 1 <= Node.val <= 10^5 1 <= low <= high <= 10^5 All Node.val are unique Example Input root = [10,5,15,3,7,null,18], low = 7, high = 15