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;

}
}