Sum Root to Leaf Numbers

Given a binary tree containing digits from

0-9

only, each root-to-leaf
path could represent a number.

An example is the root-to-leaf path

1->2->3

which represents the number

123

.

Find the total sum of all root-to-leaf numbers.

For example,

1
/ \
2   3

The root-to-leaf path

1->2

represents the number

12

.

The root-to-leaf path

1->3

represents the number

13

.

Return the sum = 12 + 13 =

25

.

/**
* Definition for binary tree
* public class TreeNode {
*     int val;
*     TreeNode left;
*     TreeNode right;
*     TreeNode(int x) { val = x; }
* }
*/
public class Solution {
public int sumNumbers(TreeNode root) {
        return sum(root, 0);
}

int sum(TreeNode root, int value){
int res=0;
if(root==null){
return 0;
}else{
int subval=value*10+root.val;
if((root.left!=null)||(root.right!=null)){
res=sum(root.left, subval)+sum(root.right, subval);
}else{
res=subval;
}
return res;
}
}
}