LeetCode 104. Maximum Depth of Binary Tree - Python

LeetCode 104. Maximum Depth of Binary Tree - Python

 

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.

 

Solution 1 (Recursive) :

class Solution:
    def maxDepth(self, root: TreeNode) -> int: 
        if not root:
            return 0
        return 1 + max(self.maxDepth(root.left), self.maxDepth(root.right))

 

Solution 2 (Recursive)  :

class Solution:
    def __init__(self):
        self.max_depth = 0

    def dfs(self, node: TreeNode, depth):
        if not node:
            return
        if self.max_depth < depth:
            self.max_depth = depth
        if node.left:
            self.dfs(node.left, depth + 1)
        if node.right:
            self.dfs(node.right, depth + 1)

    def maxDepth(self, root: TreeNode) -> int:
        if not root:
            return 0
        self.dfs(root, 1)
        return self.max_depth

 

 

 

 

 

관련 개념 설명 :

이진트리

이진트리 알고리즘

파이썬을 사용한 이진 트리와 순회 알고리즘 구현 

dfs 형식

self 이해하기
타입힌트

어노테이션(-> int:)