URL

https://leetcode.com/problems/range-sum-of-bst/description/?envType=daily-question&envId=2024-01-08

Code

https://github.com/syohex/dotnet-study/blob/master/fsharp/leetcode/challenge/202401/range_sum_of_bst/main.fsx

type Tree =
    | Leaf
    | Node of int * Tree * Tree

let rangeSumBST (root: Tree) (low: int) (high: int) : int =
    let rec rangeSumBST' node low high =
        match node with
        | Leaf -> 0
        | Node(v, left, right) ->
            let sumLeft = rangeSumBST' left low high
            let sumRight = rangeSumBST' right low high

            if v >= low && v <= high then
                v + sumLeft + sumRight
            else
                sumLeft + sumRight

    rangeSumBST' root low high