LeetCode-in-All
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:
Input: root = [3,9,20,null,null,15,7]
Output: 3
Example 2:
Input: root = [1,null,2]
Output: 2
Constraints:
- The number of nodes in the tree is in the range
[0, 104]. -100 <= Node.val <= 100
Solution
# Definition for a binary tree node.
#
# defmodule TreeNode do
# @type t :: %__MODULE__{
# val: integer,
# left: TreeNode.t() | nil,
# right: TreeNode.t() | nil
# }
# defstruct val: 0, left: nil, right: nil
# end
defmodule Solution do
@spec max_depth(root :: TreeNode.t() | nil) :: integer
def max_depth(nil), do: 0
def max_depth(root) do
max(max_depth(root.left), max_depth(root.right)) + 1
end
end