C# 把第一次出现的重复数字移动到最后

例如123455567123，变成123467123555。

        static int[] MoveFirstDupNumToEnd(int[] intArr)
        {
            int[] result = new int[intArr.Length];
            int dup = 0;
            int dupCount = 0;
            int x = 0;
            Hashtable ht = new Hashtable(intArr.Length);
            for (int i = 0; i < intArr.Length; i++)
            {
                if (ht[intArr[i]]==null)
                {
                    ht.Add(intArr[i], 1);
                }
                else
                {
                    dup = intArr[i];
                    break;
                }
            }
            for (int i = 0; i < intArr.Length; i++)
            {
                if (intArr[i] != dup)
                {
                    result[x] = intArr[i];
                    x++;
                }
                else
                {
                    dupCount++;
                }
            }
            while (dupCount>0)
            {
                result[x] = dup;
                x++;
                dupCount--;
            }
            return result;
        }