104. Maximum Depth of Binary Tree

Python

# 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
from collections import deque
class Solution:
    def maxDepth(self, root: Optional[TreeNode]) -> int:
        max_depth = 0
        que = deque()
        que.append((root, 0))
        while que:
            node, depth = que.popleft()
            if node == None:
                max_depth = max(max_depth, depth)
                continue
            que.append((node.left, depth + 1))
            que.append((node.right, depth + 1))
        
        
        return max_depth