本文主要研究了:
- 二叉树的三种遍历方式:递归和迭代实现
- 二叉树相关的例题解析
二叉树的前序遍历
递归法
# Definition for a binary tree node.
# class TreeNode:
# def __init__(self, val=0, left=None, right=None):
# self.val = val
# self.left = left
# self.right = right
class Solution:
def preorderTraversal(self, root: Optional[TreeNode]) -> List[int]:
def preorder(node):
if not node:
return
res.append(node.val)
preorder(node.left)
preorder(node.right)
res = list()
preorder(root)
return res
大约 15 分钟