C#生成不重复随机数

public static int[] GetRandNums (int seed,int total,int minimum, int maximum)
{
if (Math.Abs(maximum - minimum)+1 < total)
{
return (null);
}
int num = 0;
int[] ia = new int[total];
Random rd = new Random(seed);
for (int i = 0; i < ia.Length; i++)
{
do
{
num = rd.Next(minimum,maximum+1);
}
while (ia.Contains(num));
ia[i] = num;
}
return (ia);
}