【LeetCode OJ】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.

java code:

/**
 * Definition for binary tree
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
public class Solution {
    int res ;
    public int sumNumbers(TreeNode root) {
        // Note: The Solution object is instantiated only once and is reused by each test case.
         if(root == null)
            return 0;
         res = 0;
         sumnum(root,0);
         return res;
    }
    public void sumnum(TreeNode root, int tmpsum)
    {
        if(root.left == null && root.right == null)
        {
            res += tmpsum * 10 + root.val;
        }
        if(root.left != null)
        {
            sumnum(root.left, tmpsum * 10 + root.val);
        }
        if(root.right != null)
        {
            sumnum(root.right, tmpsum * 10 + root.val);
        }
        
        
    }
}