lintcode练习-97. 二叉树的最大深度

给定一个二叉树，找出其最大深度。

二叉树的深度为根节点到最远叶子节点的距离。

样例

给出一棵如下的二叉树:

1 / \ 2 3 / \ 4 5

这个二叉树的最大深度为3.

"""
Definition of TreeNode:
class TreeNode:
    def __init__(self, val):
        self.val = val
        self.left, self.right = None, None
"""

class Solution:
    """
    @param root: The root of binary tree.
    @return: An integer
    """
    def maxDepth(self, root):
        # write your code here
        self.depth = 0
        if not root:
            return self.depth
        q = [root]
        while q:
            self.depth += 1
            new_q = []
            for node in q:
                if node.left:
                    new_q.append(node.left)
                if node.right:
                    new_q.append(node.right)
            q = new_q
        return self.depth