题解 | #二叉树的前序遍历#

# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None
#
# 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
#
# 
# @param root TreeNode类 
# @return int整型一维数组
#
class Solution:
	#递归方法实现前序遍历
    def preorder(self,list:List[int],root:TreeNode):
        if root==None:
            return
        list.append(root.val)
        self.preorder(list,root.left)
        self.preorder(list,root.right)

    def preorderTraversal(self , root: TreeNode) -> List[int]:
        # write code here
        list=[]
        self.preorder(list,root)
        return list