Create convert-BST-to-greater-tree.java

Author: maiquynhtruong

convert-BST-to-greater-tree.java

@@ -0,0 +1,28 @@
+/**
+ * Definition for a binary tree node.
+ * public class TreeNode {
+ *     int val;
+ *     TreeNode left;
+ *     TreeNode right;
+ *     TreeNode(int x) { val = x; }
+ * }
+ 
+             10
+            /   \
+           8     13
+          / \   / \
+         5  9 12   15
+ */
+public class Solution {
+    public void convertBSTtoGT(TreeNode root, int passedDown) {
+        if (root == null) return;
+        convertBSTtoGT(root.right, 0);
+        root.val = root.val + passedDown;
+        if (root.right != null) root.val += root.right.val;
+        convertBSTtoGT(root.left, root.val);
+    }
+    public TreeNode convertBST(TreeNode root) {
+        convertBSTtoGT(root);
+        return root;
+    }
+}