🐱(tree): 104. 二叉树的最大深度 补充解法

Author: JalanJiang

docs/data-structure/tree/recursion/README.md

@@ -41,9 +41,71 @@ class Solution:
 - [原题链接](https://leetcode-cn.com/problems/maximum-depth-of-binary-tree/description/)
 - [详解链接](https://juejin.im/post/5de254ce51882523467752d0)
 
-### 思路
+### 自顶向下
+
+<!-- tabs:start -->
+
+#### **Python**
+
+```python
+# Definition for a binary tree node.
+# class TreeNode:
+# def __init__(self, x):
+# self.val = x
+# self.left = None
+# self.right = None
+
+class Solution:
+ depth = 0
+ def maxDepth(self, root: TreeNode) -> int:
+ self.depth = 0
+ self.handler(root, 1)
+ return self.depth
+ 
+ def handler(self, root, depth):
+ if root is None:
+ return
+ self.depth = max(self.depth, depth)
+ self.handler(root.left, depth + 1)
+ self.handler(root.right, depth + 1)
+```
+
+#### **Go**
+
+```go
+/**
+ * Definition for a binary tree node.
+ * type TreeNode struct {
+ * Val int
+ * Left *TreeNode
+ * Right *TreeNode
+ * }
+ */
+
+var depth int
+func maxDepth(root *TreeNode) int {
+ depth = 0
+ handler(root, 1)
+ return depth
+}
+
+func handler(root *TreeNode, curDepth int) {
+ if root == nil {
+ return
+ }
+ if curDepth > depth {
+ depth = curDepth
+ }
+ handler(root.Left, curDepth + 1)
+ handler(root.Right, curDepth + 1)
+}
+```
+
+<!-- tabs:end -->
+
+### 自底向上
 
-递归求解~
+「自底向上」：我们首先对所有子节点递归地调用函数，然后根据返回值和根节点本身的值得到答案。
 
 取左右子树最大深度值 + 1（1 为到 root 节点的深度）