Merge pull request #881 from hailincai/patch1029

Update 0104.二叉树的最大深度.md

problems/0104.二叉树的最大深度.md

@@ -312,6 +312,24 @@ class solution {
 ```
 
 ### 559.n叉树的最大深度 
+```java
+class Solution {
+    /*递归法，后序遍历求root节点的高度*/
+    public int maxDepth(Node root) {
+        if (root == null) return 0;
+
+        int depth = 0;
+        if (root.children != null){
+            for (Node child : root.children){
+                depth = Math.max(depth, maxDepth(child));
+            }
+        }
+
+        return depth + 1; //中节点
+    }  
+}
+```
+
 ```java
 class solution {
     /**