maximum-depth-of-binary-tree.py

# 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
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#
#  
# Constraints:
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#
# 	The number of nodes in the tree is in the range [0, 104].
# 	-100 <= Node.val <= 100
#
#


# 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: TreeNode) -> int:
        if root == None:
            return 0
        else:
            left = self.maxDepth(root.left)
            right = self.maxDepth(root.right)
            if left > right:
                return left+1
            else:
                return right+1