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/**
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 * Definition for a binary tree node.
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 * function TreeNode(val, left, right) {
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 *     this.val = (val===undefined ? 0 : val)
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 *     this.left = (left===undefined ? null : left)
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 *     this.right = (right===undefined ? null : right)
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 * }
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 */
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/**
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 * @param {TreeNode} root
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 * @return {number}
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 */
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var sumNumbers = function (root) {
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  return dfs(root);
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};
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const dfs = (root, path = "") => {
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  if (!root.left && !root.right) return +(path + root.val);
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  const left = root.left ? dfs(root.left, path + root.val) : 0;
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  const right = root.right ? dfs(root.right, path + root.val) : 0;
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  return left + right;
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};