Java for Leetcode 129 Sum Root to Leaf Numbers

Given a binary tree containing digits from only 0-9 , 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 = + = 25 .

Problem Solving Ideas:

Recursively, the Java implementation is as follows:

    static public int sumnumbers (TreeNode root) {    if (root==null)    return 0;        Return Sumnumbers (root,0);    }    public static int Sumnumbers (TreeNode root,int res) {    if (root.left==null&&root.right==null)    return Res*10+root.val;    if (root.left==null)    return sumnumbers (root.right,res*10+root.val);    if (root.right==null)    return sumnumbers (root.left,res*10+root.val);    Return Sumnumbers (Root.left,res*10+root.val) +sumnumbers (root.right,res*10+root.val);    }

Java for Leetcode 129 Sum Root to Leaf Numbers