104. Maximum Depth of Binary Tree

https://leetcode.com/problems/maximum-depth-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.

Note: A leaf is a node with no children.
图算法
算法一： 用递归 DFS 深度优先搜索
算法二： BFS 广度优先搜索

# 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 root==None: return 0
        return max(self.maxDepth(root.left),self.maxDepth(root.right)) + 1
# 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
        """
        print([False])
        depth = 0
        level = [root] if root else []
        while level:
            depth += 1
            queue = []
            for el in level:
                if el.left:
                    queue.append(el.left)
                if el.right:
                    queue.append(el.right)
            level = queue
        return depth

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