题解 | #二叉树的前序遍历#
二叉树的前序遍历
https://www.nowcoder.com/practice/5e2135f4d2b14eb8a5b06fab4c938635
from typing import List
class TreeNode:
def __init__(self, x):
self.val = x
self.left = None
self.right = None
def preorderTravelsal(root: TreeNode) -> TreeNode:
lists = []
preorder(lists, root)
return lists
def preorder(list: List[int], root: TreeNode):
if root == None:
return None
# 先遍历根节点
list.append(root.val)
# 再去左子树
preorder(list, root.left)
# 再去右子树
preorder(list, root.right)
if __name__ == '__main__':
# lists = input().split(',')
root = TreeNode(1)
root.left = None
root.right = TreeNode(2)
root.right.left = TreeNode(3)
result = preorderTravelsal(root)
print(result)
