Given an n-ary tree, return the preorder traversal of its nodes‘ values.
For example, given a 3-ary tree:
Return its preorder traversal as: [1,3,5,6,2,4].
这个题目思路就是跟LeetCode questions conlusion_InOrder, PreOrder, PostOrder traversal类似, recursive 和iterable都可以.
1. Recursively
class Solution: def nary_Preorder(self, root): def helper(root): if not root: return ans.append(root.val) for each in root.children: if each: helper(each) ans = [] helper(root) return ans
2. Iterable
class Solution: def nary_preOrder(self, root): if not root: return [] stack, ans = [root], [] while stack: node = stack.pop() ans.append(node.val) for each in node.children[::-1]: if each: stack.append(each) return ans
[LeetCode] 589. N-ary Tree Preorder Traversal_Easy
原文：https://www.cnblogs.com/Johnsonxiong/p/9348912.html