104. Maximum Depth of Binary Tree
Easy
Given the root of a binary tree, return its maximum depth.
A binary tree's maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.
Example 1:
Example 2:
Constraints:
- The number of nodes in the tree is in the range [0, 104].
- -100 <= Node.val <= 100
Solution
class Solution:
def maxDepth(self, root: Optional[TreeNode]) -> int:
return self.helper(root, 0)
def helper(self, root, res):
if root is None:
return res
else:
return max(
self.helper(root.left, res + 1), self.helper(root.right, res + 1)
)
class TreeNode:
def __init__(self, val=0, left=None, right=None):
self.val = val
self.left = left
self.right = right