Merge pull request #96 from Joshua-Lu/patch-12

添加 0538.把二叉搜索树转换为累加树 Java版本

problems/0538.把二叉搜索树转换为累加树.md

@@ -173,20 +173,24 @@ public:
 
 
 Java：
-```java
+```Java
 class Solution {
-    private int count = 0;
+    int sum;
     public TreeNode convertBST(TreeNode root) {
-        convert(root);
+        sum = 0;
+        convertBST1(root);
         return root;
     }
 
-    private void convert (TreeNode root) {
-        if (root == null) return;
-        convert(root.right);
-        count += root.val;
-        root.val = count;
-        convert(root.left);
+    // 按右中左顺序遍历，累加即可
+    public void convertBST1(TreeNode root) {
+        if (root == null) {
+            return;
+        }
+        convertBST1(root.right);
+        sum += root.val;
+        root.val = sum;
+        convertBST1(root.left);
     }
 }
 ```