//获得每个节点的信息,并显示,这里用到了linq查询
IList<TreeInfo> GetNodes(IList<TreeInfo> list, int levelId, int left, int right)
{
var q = from ct in list
where ct.Level == levelId
select ct;
if (left != 0 && right != 0)
q = q.Where(w => w.Left > left & w.Right < right);
return q.ToList();
}