不重复随机

    public static List<T> MyRandom<T>(ref List<T> tras, int number)
    {
        if (number > tras.Count)
        {
            Debug.Log("要取的个数大于数组长度！");
            return null;
        }

        List<T> result = new List<T>();
        List<int> Numid = new List<int>();

        for (int i = 0; i < tras.Count; i++)
        {
            Numid.Add(i);
        }

        int r;
        while (Numid.Count > tras.Count - number)
        {
            r = UnityEngine.Random.Range(0, Numid.Count);
            result.Add(tras[Numid[r]]);
            Numid.Remove(Numid[r]);
        }
        return (result);
    }