Delete Duplicate Folders in System LeetCode solution in JavaScript

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class Node {
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  constructor(val, parent) {
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    (this.val = val), (this.parent = parent), (this.children = {}), this.hash;
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  }
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}
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class Trie {
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  constructor() {
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    this.root = new Node("");
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    this.hashMemo = {};
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  }
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  insert(path) {
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    let cur = this.root;
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    for (let node of path)
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      if (cur.children[node] !== undefined) cur = cur.children[node];
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      else
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        (cur.children[node] = new Node(node, cur)), (cur = cur.children[node]);
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  }
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  traverse(node = this.root) {
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    node.hash = [];
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    if (node.children)
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      for (let child of Object.values(node.children))
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        node.hash.push(this.traverse(child));
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    node.hash = node.hash.join("~");
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    if (node.hash !== "") {
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      if (this.hashMemo[node.hash] === undefined) this.hashMemo[node.hash] = [];
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      this.hashMemo[node.hash].push(node);
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      return node.val + "/[" + node.hash + "]";
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    }
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    return node.val;
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  }
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  delete(node = this.root) {
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    if (!node || node.hash === undefined) return;
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    else if (this.hashMemo[node.hash] && this.hashMemo[node.hash].length > 1)
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      for (let todelete of this.hashMemo[node.hash])
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        delete todelete.parent.children[todelete.val];
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    else for (let child of Object.values(node.children)) this.delete(child);
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  }
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  serialize(node = this.root, stack = [], res = []) {
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    if (node.val !== "") stack.push(node.val), res.push([...stack]);
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    for (let child of Object.values(node.children))
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      this.serialize(child, stack, res);
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    stack.pop();
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    return res;
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  }
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}
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var deleteDuplicateFolder = function (paths) {
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  let T = new Trie();
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  for (let P of paths) T.insert(P);
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  T.traverse();
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  T.delete();
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  return T.serialize();
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};