path-sum Java code

Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the given sum.
For example:
Given the below binary tree andsum = 22,
5
/ \
4 8
/ / \
11 13 4
/ \ \
7 2 1
return true, as there exist a root-to-leaf path5->4->11->2which sum is 22.

/** * Definition for binary tree * public class TreeNode { *     int val; *     TreeNode left; *     TreeNode right; *     TreeNode(int x) { val = x; } * } */public class Solution {    public boolean hasPathSum(TreeNode root, int sum) {        if(root==null)          return false;        int now=0;        return  digui(root,sum,now);    }    boolean digui(TreeNode root, int sum,int now){         now+=root.val;        if(sum==now&&root.left==null&&root.right==null){            return true;        }        boolean left=false,right=false;         if(root.left!=null)             left= digui(root.left,sum,now);        if(root.right!=null)             right= digui(root.right,sum,now);        return left||right;    }}