Hot-104 二叉树的最大深度

1、解法1：递归

# 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 maxDepth(self, root: Optional[TreeNode]) -> int: if not root: return 0 def dfs(node): # 出口： if not node: return 0 left_depth = dfs(node.left) + 1 right_depth = dfs(node.right) + 1 return max(left_depth,right_depth) ans = dfs(root) return ans