[原题链接](https://leetcode-cn.com/problems/n-ary-tree-preorder-traversal/solution/qian-duan-shi-tang-ti-jie-chao-hao-li-ji-6gok/) ## 递归 dfs ```javascript const preorder = function(root) { if (root === null) return [] const res = [] function dfs(root) { if (root === null) return res.push(root.val) for (let i = 0; i < root.children.length; i++) { dfs(root.children[i]) } } dfs(root) return res } ``` - 时间复杂度：O(n) - 空间复杂度：O(n)
