'''
Source : https://leetcode.com/problems/maximum-depth-of-binary-tree/
Author : <NAME>
Date   : 2018-07-21

/********************************************************************************** 
*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.
*
*Note: A leaf is a node with no children.
*
*Example:
*
*Given binary tree [3,9,20,null,null,15,7],
*
*	3
*   / \
*  9  20
*	/  \
*   15   7
*return its depth = 3.
**********************************************************************************/
'''

def maxDepth(self, root):
	"""
	:type root: TreeNode
	:rtype: int
	"""
	depth=0
	return self.calDepth(root,depth)
	
def calDepth(self,root,depth):
	if root:
		depth+=1
		return max(self.calDepth(root.left,depth),self.calDepth(root.right,depth))
	
	return depth
'''
Source : https://leetcode.com/problems/maximum-depth-of-binary-tree/
Author : <NAME>
Date   : 2018-07-21

/********************************************************************************** 
*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.
*
*Note: A leaf is a node with no children.
*
*Example:
*
*Given binary tree [3,9,20,null,null,15,7],
*
*	3
*   / \
*  9  20
*	/  \
*   15   7
*return its depth = 3.
**********************************************************************************/
'''

def maxDepth(self, root):
	"""
	:type root: TreeNode
	:rtype: int
	"""
	depth=0
	return self.calDepth(root,depth)
	
def calDepth(self,root,depth):
	if root:
		depth+=1
		return max(self.calDepth(root.left,depth),self.calDepth(root.right,depth))
	
	return depth
Source : https://leetcode.com/problems/maximum-depth-of-binary-tree/ Author : <NAME> Date   : 2018-07-21  /**********************************************************************************  *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. * *Note: A leaf is a node with no children. * *Example: * *Given binary tree [3,9,20,null,null,15,7], * *	3 *   / \ *  9  20 *	/  \ *   15   7 *return its depth = 3. **********************************************************************************/ :type root: TreeNode 	:rtype: int