不重複隨機數(int)

以下本代碼是用C#實現時間複雜度為O(n)的演算法.int[] myIntArray(int begin, int end, int num)用於產生num個在範圍[begin,end]內的不重複隨機數.int[] myIntArray(int begin, int end)用於產生範圍[begin,end]內隨機排列.

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;
        }