algorithms/429-n-ary-tree-level-order-traversal.ipynb

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    "### [N叉树的层序遍历](https://leetcode-cn.com/problems/n-ary-tree-level-order-traversal/)\n",
    "\n",
    "\n",
    "给定一个`N`叉树，返回其节点值的层序遍历。（即从左到右，逐层遍历）。\n",
    "\n",
    "树的序列化输入是用层序遍历，每组子节点都由`null`值分隔（参见示例）。\n",
    "\n",
    "#### 示例 1：\n",
    "```\n",
    "输入：root = [1,null,3,2,4,null,5,6]\n",
    "输出：[[1],[3,2,4],[5,6]]\n",
    "```\n",
    "\n",
    "#### 示例 2：\n",
    "```\n",
    "输入：root = [1,null,2,3,4,5,null,null,6,7,null,8,null,9,10,null,null,11,null,12,null,13,null,null,14]\n",
    "输出：[[1],[2,3,4,5],[6,7,8,9,10],[11,12,13],[14]]\n",
    "```\n",
    "\n",
    "#### 提示：\n",
    "```\n",
    "树的高度不会超过 1000\n",
    "树的节点总数在 [0, 10^4] 之间\n",
    "```\n",
    "\n",
    "#### 相关题目\n",
    "\n",
    "- [100. 相同的树](https://leetcode-cn.com/problems/same-tree/)\n",
    "- [101. 对称二叉树](https://leetcode-cn.com/problems/symmetric-tree/)\n",
    "- [102. 二叉树的层序遍历](https://leetcode-cn.com/problems/binary-tree-level-order-traversal/)\n",
    "- [103. 二叉树的锯齿形层序遍历](https://leetcode-cn.com/problems/binary-tree-zigzag-level-order-traversal/)\n",
    "- [104. 二叉树的最大深度](https://leetcode-cn.com/problems/maximum-depth-of-binary-tree/)\n",
    "- [107. 二叉树的层序遍历 II](https://leetcode-cn.com/problems/binary-tree-level-order-traversal-ii/)\n",
    "- [111. 二叉树的最小深度](https://leetcode-cn.com/problems/minimum-depth-of-binary-tree/)\n",
    "- [429. N叉树的层序遍历](https://leetcode-cn.com/problems/n-ary-tree-level-order-traversal/)\n",
    "- [559. N叉树的最大深度](https://leetcode-cn.com/problems/maximum-depth-of-n-ary-tree/)\n",
    "- [589. N叉树的前序遍历](https://leetcode-cn.com/problems/n-ary-tree-preorder-traversal/)\n",
    "- [590. N叉树的后序遍历](https://leetcode-cn.com/problems/n-ary-tree-postorder-traversal/)\n",
    "- [剑指 Offer 28. 对称的二叉树](https://leetcode-cn.com/problems/dui-cheng-de-er-cha-shu-lcof/)\n",
    "- [剑指 Offer 32 - I. 从上到下打印二叉树](https://leetcode-cn.com/problems/cong-shang-dao-xia-da-yin-er-cha-shu-lcof/)\n",
    "- [剑指 Offer 32 - II. 从上到下打印二叉树 II](https://leetcode-cn.com/problems/cong-shang-dao-xia-da-yin-er-cha-shu-ii-lcof/)\n",
    "- [剑指 Offer 32 - III. 从上到下打印二叉树 III](https://leetcode-cn.com/problems/cong-shang-dao-xia-da-yin-er-cha-shu-iii-lcof/)\n",
    "- [剑指 Offer 55 - I. 二叉树的深度](https://leetcode-cn.com/problems/er-cha-shu-de-shen-du-lcof/)"
   ]
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  {
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   "source": [
    "from typing import List\n",
    "\n",
    "class Node:\n",
    "    def __init__(self, val=None, children=None):\n",
    "        self.val = val\n",
    "        self.children = children\n",
    "\n",
    "class Solution:\n",
    "    def levelOrder(self, root: Node) -> List[List[int]]:\n",
    "        if not root:\n",
    "            return []\n",
    "        \n",
    "        queue, ans = [root], []\n",
    "        while queue:\n",
    "            n, a = len(queue), []\n",
    "            for i in range(n):\n",
    "                node = queue.pop(0)\n",
    "                a.append(node.val)\n",
    "                if node.children:\n",
    "                    for child in node.children:\n",
    "                        queue.append(child)\n",
    "            ans.append(a)\n",
    "            \n",
    "        return ans"
   ]
  }
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