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import { TreeNode } from "../binary-tree-inorder-traversal/TreeNode.ts";
export default function rangeSumBST(    root: TreeNode | null,    low: number,    high: number,): number {    if (!root) {        return 0;    }    const current: TreeNode[] = [root];    let result = 0;    level(current, low, high, (r) => {        for (const n of r) {            if (low <= n && n <= high) {                result += n;            }        }    });    return result;}
function level(    nodes: TreeNode[],    low: number,    high: number,    output: (r: number[]) => void,) {    if (nodes.length === 0) {        return;    }
    output(nodes.map((n) => n.val));
    level(        nodes            .map((n) => {                if (n.val > high) {                    return n.left;                }                if (n.val < low) {                    return n.right;                }                return [n.left, n.right].filter(Boolean) as TreeNode[];            })            .flat()            .filter(Boolean) as TreeNode[],        low,        high,        output,    );}