С# solution (Half of difficulty its figure out what the task is actually...)

Task explanation(if someone needed): We have an input : [[type, x, y]] , where type - type of queries( if 1 - add y in list(using formula), if 2 - extract element using second formula and add to lastAnswer ). x - parametr, what we using in formula which calculate index where we need to insert/extract y. y - parameter, what we insert/extract.

{
    List<List<int>> seqList = new List<List<int>>();
    for (int i = 0; i < n; i++)
    {
        seqList.Add(new List<int>());
    }

    List<int> results = new List<int>();
    int lastAnswer = 0;

    foreach (var query in queries)
    {
        int type = query[0];
        int x = query[1];
        int y = query[2];
        int seqIndex = (x ^ lastAnswer) % n;

        if (type == 1)
        {
            seqList[seqIndex].Add(y);
        }
        else if (type == 2)
        {
            int size = seqList[seqIndex].Count;
            lastAnswer = seqList[seqIndex][y % size];
            results.Add(lastAnswer);
        }

    }

    return results;
}