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import { TreeNode } from "../binary-tree-inorder-traversal/TreeNode.ts";
export default function recoverFromPreorder(    traversal: string,): TreeNode | null {    const depth_to_tree = new Map<number, TreeNode>();    for (const [depth, value] of parse(traversal)) {        const tree = new TreeNode(value);        if (depth > 0) {            const parent = depth_to_tree.get(depth - 1);            if (parent) {                if (parent.left) parent.right = tree;                else {                    parent.left = tree;                }            }        }        depth_to_tree.set(depth, tree);    }    return depth_to_tree.get(0) ?? null;}function* parse(s: string): Generator<[number, number]> {    let depth = 0;    let value = 0;    const len = s.length;    for (let i = 0; i < len; i++) {        if (s[i] === "-") {            depth++;            continue;        }        while (i < len && /\d/.test(s[i])) {            value = value * 10 + Number(s[i]);            i++;        }        i--;        yield [depth, value];        depth = 0;        value = 0;    }}