JAVA 面试题 【快速获取第N个素数】

static long GetNPrime(int count)//返回第count个素数
{
    List<long> list = new List<long>();//顺序存放素数
    long startNumber = 1;
    while (list.Count < count)
    {
        if (IsPrime(startNumber, list)) list.Add(startNumber);
        startNumber++;
    }
    return --startNumber;
}

static bool IsPrime(long number, List<long> list)//判断number是否为素数
{
    if (number == 1) return false;
    long max = (long)Math.Sqrt(number);
    foreach (long n in list)
    {
        if (number % n == 0) return false;
        if (n > max) break;
    }
    return true;
}