Check If a String Is a Valid Sequence from Root to Leaves Path in a Binary Tree

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode() {}
 *     TreeNode(int val) { this.val = val; }
 *     TreeNode(int val, TreeNode left, TreeNode right) {
 *         this.val = val;
 *         this.left = left;
 *         this.right = right;
 *     }
 * }
 */
class Solution {
    public boolean isValidSequence(TreeNode root, int[] arr) {
        return helper(root, arr, 0);
    }
    public boolean helper(TreeNode root, int[] arr, int index){
        if(root == null || index == arr.length){
            return false;
        }
        if(root.left == null && root.right == null && root.val == arr[index] && index == arr.length-1){
             return true;
        }
        return root.val == arr[index] && (helper(root.left, arr, index+1) || helper(root.right, arr, index+1));
    }
}