Convert a given tree to sum tree

This is a solution to here: link

1. public class BuildSumTree {
3.     public static void main(String[] args) {
4.         Tree tree = getSumTree();
5.         tree = convertToSumTree(tree);
6.     }
8.     /*
9.      * http://www.geeksforgeeks.org/convert-a-given-tree-to-sum-tree/
10.      */
11.     public static int convertToSumTree(Tree tree){
12.         if(tree==null){
13.             return 0;
14.         }
15.         int lvalue = (tree.left==null)?0:tree.left.value;
16.         int rvalue = (tree.right==null)?0:tree.right.value;
17.         tree.value = convertToSumTree(tree.left) + convertToSumTree(tree.right) + lvalue + rvalue;
18.         return tree.value;
19.     }
21.     /*
22.      * This tree will be converted to a sum tree.
23.      */
24.     public static Tree getSumTree(){
25.         Tree t1 = new Tree(1);
26.         Tree t2 = new Tree(2);
27.         Tree t3 = new Tree(3);
28.         Tree t4 = new Tree(4);
29.         Tree t5 = new Tree(5);
30.         Tree t6 = new Tree(6);
31.         t1.left = t2;
32.         t1.right = t3;
33.         t2.left = t4;
34.         t2.right = t5;
35.         t3.left = t6;
36.         return t1;
37.     }
38. }