树中是否存在路径和为 sum leecode java

/**
* 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;
if(root.left==null&&root.right==null)
{
if(sum==root.val) return true;

}

return hasPathSum(root.left,sum-root.val)||hasPathSum(root.right,sum-root.val);

}
}