题解 | #求二叉树的层序遍历#

#     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整型二维数组
#
class Solution:
    def __init__(self):
        self.res = []
    def levelOrder(self , root: TreeNode) -> List[List[int]]:
        # write code here
        if not root:
            return []
        self.dfs(1,root)
        return self.res
    
    def dfs(self,index,r):
        if len(self.res) < index:
            self.res.append([])
        self.res[index - 1].append(r.val)
        if r.left:
            self.dfs(index + 1, r.left)
        if r.right:
            self.dfs(index + 1, r.right)