maximum-depth-of-binary-tree.py

from __future__ import print_function
# Time:  O(n)
# Space: O(h), h is height of binary tree
#
# Given a binary tree, find its maximum depth.
#
# The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.
#

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

class Solution:
    # @param root, a tree node
    # @return an integer
    def maxDepth(self, root):
        if root is None:
            return 0
        else:
            return max(self.maxDepth(root.left), self.maxDepth(root.right)) + 1

if __name__ == "__main__":
    root = TreeNode(1)
    root.left = TreeNode(2)
    root.right = TreeNode(3)
    root.left.left = TreeNode(4)
    print(Solution().maxDepth(root))