不重复随机数(int)

以下本代码是用C#实现时间复杂度为O(n)的算法.int[] myIntArray(int begin, int end, int num)用于产生num个在范围[begin,end]内的不重复随机数.int[] myIntArray(int begin, int end)用于产生范围[begin,end]内随机排列.

public int[] myIntArray(int begin, int end, int num)
        {
            int[] intArrayResult = new int[num];
            int span = end - begin;
            if (end >= begin && (end - begin) >= num && begin >= 0)
            {
                Random rnd = new Random(System.DateTime.Now.Millisecond);
                ArrayList tempArray = new ArrayList();
                               
                for (int i = begin; i < end + 1; i++)
                {
                    tempArray.Add(i.ToString());
                }
                for (int j = 0; j < num; j++)
                {
                    int no = rnd.Next(span - j - 1);
                    int temp = System.Convert.ToInt32(tempArray[no]);
                    intArrayResult[j] = temp;
                    tempArray.Remove(intArrayResult[j].ToString());
                }
            }
            return intArrayResult;
                       
        }

        public int[] myIntArray(int begin, int end)
        {
            int num = end - begin + 1;
            int[] intArrayResult = new int[num];

            if (end >= begin && begin >= 0)
            {
                Random rnd = new Random(System.DateTime.Now.Millisecond);
                ArrayList tempArray = new ArrayList();

                for (int i = begin; i < end + 1; i++)
                {
                    tempArray.Add(i.ToString());
                }

                for (int j = 0; j < num; j++)
                {
                    int no = rnd.Next(num - j - 1);
                    int temp = System.Convert.ToInt32(tempArray[no]);
                    intArrayResult[j] = temp;
                    tempArray.Remove(intArrayResult[j].ToString());
                }
            }
            return intArrayResult;
        }