Maximum Depth of Binary Trees

Problem: Maximum Depth of Binary Trees

The solution is just a complete depth-first search.

Code in Python:

# Definition for a binary tree node.
# class TreeNode(object):
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

class Solution(object):
    def maxDepth(self, root):
        """
        :type root: TreeNode
        :rtype: int
        """
        if not root: return 0

        def dfs(node, depth):
            if not node.left and not node.right: return depth+1
            left = right = 0
            if node.left: left = dfs(node.left, depth+1)
            if node.right: right = dfs(node.right, depth+1)
            return max(left, right)

        return dfs(root, 0)