C# 将列表拆分为 n 组的所有组合 - 来自 Python 的代码迁移

我所追求的算法有一个很好的实现here https://stackoverflow.com/questions/39192777/python-split-a-list-into-n-groups-in-all-possible-combinations-of-group-length-a/ (by @懒狗 https://stackoverflow.com/users/6732794/lazy-dog）。然而，我在 C# 中需要这个，并且由于 C# 缺乏yield from也许还有我自己的愚蠢。

这是我目前拥有的：

public static IEnumerable<ArrayList> sorted_k_partitions(int[] seq, int k) {
  var n = seq.Length;
  var groups = new ArrayList(); //a list of lists, currently empty

  IEnumerable<ArrayList> generate_partitions(int i) {
    if (i >= n) {
      // this line was the bug, was not creating a 
      //   deep clone of the list of lists
      // yield return new ArrayList(groups); 
      yield return new ArrayList(groups.ToArray().Select(g => ((List<int>)g).ToList())); 
      // Ugly but that is because we are using ArrayList
      // Using proper List<List<int>> cleans this up significantly
    }
    else {
      if (n - i > k - groups.Count)
        foreach (List<int> group in new ArrayList(groups)) {
          group.Add(seq[i]);
          // yield from generate_partitions(i + 1);
          foreach (var d in generate_partitions(i + 1)) {
            yield return d;
          }
          group.RemoveAt(group.Count - 1);
        }

      if (groups.Count < k) {
        groups.Add(new List<int> {seq[i]});
        foreach (var d in generate_partitions(i + 1)) {
          // things start breaking down here, as this yield return
          //  appears to release flow control and we then get the 
          //  yield return above.  I have debuged this and the python
          //  version and the python version does not do this.  Very hard
          //  to explain considering I don't fully understand it myself
          yield return d;
        }
        groups.RemoveAt(groups.Count - 1);
      }
    }
  }
  return generate_partitions(0);
  // don't worry about the sorting methods in the python 
  //   version, not needed
}

任何人都可以看到任何明显的错误，我确信我对Python缺乏理解yield from协程在这里伤害了我。

编辑：发现错误，在上面添加评论

你在这里有什么行为？

在我看来yield return generate_partitions(i + 1);而不是 foreach 循环应该可以正常工作。它只会使用新值递归调用该函数i+1