public class Solution    {        public IList
     
       PowerfulIntegers(int x, int y, int bound)        {                        var list = new List
      
       ();            for (int i = 0; i < bound; i++)            {                for (int j = 0; j < bound; j++)                {                    var num =                        Math.Pow((double)x, (double)i)                        +                        Math.Pow((double)y, (double)j);                    if (num <= bound)                    {                        list.Add((int)num);                    }                    else                    {                        if (j == 0)                        {                            return list.Distinct().OrderBy(a => a).ToList();                        }                        else                        {                            break;//换行                        }                    }                }            }            return list.Distinct().OrderBy(a => a).ToList();        }    }