为什么在线java ide解决方案抛出“error:<identifier>expected”?

我在leetcode.com解决这个问题

我一点也不想找到解决办法。我不明白,为什么我在这里检查其他答案却得到这个错误。

问题: 给定一棵二叉树,找出路径中每个节点具有相同值的最长路径的长度。此路径可能通过也可能不通过根。

注意:两个节点之间的路径长度由它们之间的边数表示。

例1:

输入:

          5
         / \
        4   5
       / \   \
      1   1   5

输出:

2

下面是我的代码

Line 25: error: <identifier> expected

在 public int longestUnivaluePathHelper(TreeNode root, int long, int prevLongest, int totalHeight)

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
// rule 1: the univalue can be either left side or right side
// rule 2: it need not go thru root
// rule 3: height < 1000
/*

        1
     2     3

*/

class Solution {
    public int longestUnivaluePath(TreeNode root) {
        return longestUnivaluePathHelper(root,1,1,1);
    }

    public int longestUnivaluePathHelper(TreeNode root, int long, int prevLongest, int totalHeight){
        if(totalHeight >= 1000){
            return prevLongest;
        }
        if(root.left == null || root.right == null){
            return prevLongest;
        }else{
            if(root.val == root.left ){
                long++;                
            }else if(root.val == root.right){
                long++;
            }else{
                prevLongest = long;
                long = 1;
                totalHeight++;
            }
            longestUnivaluePathHelper(root.left, long, prevLongest, totalHeight);
            longestUnivaluePathHelper(root.right, long, prevLongest, totalHeight);
        }
        //return prevLongest;
    }
}