Li Kou daily question - Day 32 -589 N × Preorder traversal of tree

2022.7.1 Did you brush the questions today

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subject ：

Given a n  The root node of the fork tree  root , return Of its node value The former sequence traversal .

n Fork tree In the input sequence traversal serialization representation , Each group of child nodes consists of null values null Separate （ See example ）.

analysis ：

For the preorder of binary tree , Middle preface , Follow up traversal problem , Look at this very nice

The first card ： Or so mobile

Second card ： Direct traversal

「 Random code recording 」 Thoroughly understand the recursive method of front, middle and rear order （ Recursive Trilogy ） And iterative method （ Non unified writing and unified writing ） - N Preorder traversal of a cross tree - Power button （LeetCode）https://leetcode.cn/problems/n-ary-tree-preorder-traversal/solution/che-di-chi-tou-qian-zhong-hou-xu-di-gui-fa-di-gui-/N Preorder traversal of a cross tree - N Preorder traversal of a cross tree - Power button （LeetCode）https://leetcode.cn/problems/n-ary-tree-preorder-traversal/solution/n-cha-shu-de-qian-xu-bian-li-by-leetcode-bg99/