题解 | #二叉树的前序遍历#
二叉树的前序遍历
https://www.nowcoder.com/practice/5e2135f4d2b14eb8a5b06fab4c938635
# class TreeNode: # def __init__(self, x): # self.val = x # self.left = None # self.right = None class Solution: def preorderTraversal(self, root: TreeNode) -> List[int]: if not root: return [] res = [] def dfs(node: TreeNode): res.append(node.val) if node.left: dfs(node.left) if node.right: dfs(node.right) dfs(root) return res