package code;
/*
 * 538. Convert BST to Greater Tree
 * +
 * Easy
 * Tree
 * 
 *      
 * Tips
 */
public class lc538 {
    public class TreeNode {
        int val;
        TreeNode left;
        TreeNode right;
        TreeNode(int x) { val = x; }
    }
    int sum = 0;
    public TreeNode convertBST(TreeNode root) {
        if(root==null) return null;
        convertBST(root.right);
        sum += root.val;
        root.val = sum;
        convertBST(root.left);
        return root;
    }
}