循环遍历两个列表，从列表#2中删除重复项

我有一个目录的文件名数组(aryfilename)。我有一个CSV文件的文件名列表(lstKeepers)。这个列表是目录中应该包含的文件的列表。我所做的就是在目录中查找孤儿文件。

我已经重做了这个逻辑3次了，每次我最终都遇到了一个需要重做的问题，所以我只是想问一下我应该如何处理这个问题。

我当前的逻辑是:

List<string> lstKeepers = new List<string>(aryKeepers);
DirectoryInfo dir = new DirectoryInfo(txtMSALoc.Text);
FileInfo[] attFiles = dir.GetFiles();
//variable for testing if a keeper was found.
bool bolTest = false;
//Loop through the directory's files
foreach (FileInfo attFile in attFiles)
{
    //Loop through the list of keepers
    foreach (string lstKeeper in lstKeepers){
        if (lstKeeper == attFile.Name)
        {
            //This file is a keeper not an orphan, remove it from the list.
            // This line doesn't actually work.  Is a List the right way to go?
            lstKeepers(lstKeeper).remove;
            bolTest = true;
            break;
        }
    }
    // Code fell out of the loop, see if it found a keeper.
    if (bolTest)
    {
        bolTest=false;
    }
    else
    {
        //CODE TO MOVE FILE INTO ORPHAN DIRECTORY
    }
}

我正在处理多达200万个文件的潜在目录(和看守列表)，所以这就是我想用它找到的每个文件不断缩小看守列表的原因，所以它运行的时间应该越长越快。

所以我的第一个问题是，有没有更好的方法来做到这一点?

我的下一个问题是，数组和列表是最好的东西吗?当你需要删除一些内容时，我发现linkedlist会更好。

以下是我之前的尝试:

1)同时循环遍历目录列表和keeper列表:由于两者在很大程度上都是数值file.name = 123, file.name = 124等等，我只是比较了文件名的值，并根据当前对是否为<或> each other或=。但由于缺乏自然排序，这不起作用。

2)只使用两个数组，但是从数组中删除项是不实际的(因为我必须不断重新创建数组)。

3)(目前)这似乎是我可以删除项目的方式，但后来有人说要使用LinkedLists来删除项目，因为我厌倦了重新启动这个项目，这是打破编码员背部的稻草:)

任何建议都是感激的!

更新:这是最终版本，非常感谢大家的帮助!

            string[] aryKeepers;
            if (File.Exists("Keepers.csv"))
            {
                aryKeepers = File.ReadAllLines("Keepers.csv");
            }
            else
            {
                MessageBox.Show("Cannot find 'Keepers.csv' file.", "Missing CSV File Error", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
                aryKeepers = null;
                return;
            }
            List<string> lstKeepers = new List<string>(aryKeepers);
            DirectoryInfo dir = new DirectoryInfo(txtMSALoc.Text);
            FileInfo[] attFiles = dir.GetFiles();
            List<string> lstOrphans = attFiles
                                        .Where(x => !lstKeepers.Contains(x.Name))
                                        .Select(x => x.Name)
                                        .ToList();
            if (lstOrphans.Count > 0){
                intOrphan = lstOrphans.Count;
                lstOrphans.ForEach (lstOrphan => {
                    string strOldFile = txtMSALoc.Text + @"'" + lstOrphan;
                    string strNewFile = dirOrphan + lstOrphan;
                    File.Move(strOldFile, strNewFile);
                });
            }

List<string> orphans = new List<string>();
// Enumerate files in directory
foreach(string file in attFiles)
{
    // If the filename isn't in the keepers list it must be 
    // an orphan, add it to the orphans list
    if(!lstKeepers.Contains(file.Name))
        orphans.Add(file.Name);
}

foreach(string orphanedFile in orphans)
{ 
    // Move the file
}

List<string> orphans = attFiles
                            .Where(x => !lstKeepers.Contains(x.Name))
                            .Select(x => x.Name)
                            .ToList();

orphans.ForEach(orphan => { // Do something });

FileInfo[] attFiles = new DirectoryInfo(txtMSALoc.Text).GetFiles();
HashSet<string> att = new HashSet<string>(attFiles.Select(a => a.Name));
foreach (string attFile in aryKeepers.Where(s => att.Contains(s))) {
  //CODE TO MOVE FILE INTO ORPHAN DIRECTORY
}

HashSet<string> lstKeepers = new HashSet<string>(aryKeepers);
DirectoryInfo dir = new DirectoryInfo(txtMSALoc.Text);
FileInfo[] attFiles = dir.GetFiles();
//Loop through the directory's files
foreach (FileInfo attFile in attFiles)
{
    if (lstKeepers.Contains(attFile.Name))
    {
        //CODE TO MOVE FILE INTO ORPHAN DIRECTORY
        //remove from the HashSet
        lstKeepers.Remove(attFile.Name);
    }
}