产生不重复的随机数

  class MyRand
    {
        private int seed;
        private int prevNumber = 10;
        public MyRand(int seed)
        {
            this.seed = seed;
        }

        public int Next()
        {
            int newRand = (seed + prevNumber) % 100;
            prevNumber = newRand;
            return newRand;
        }
    }


 List<int> list = new List<int>();
            Random rand = new Random();
            while (list.Count < 100)
            {
                int number = rand.Next(1, 101);//>=1,<101
                if (!list.Contains(number))//如果list中已经含有这个数，则不插入
                {
                    list.Add(number);
                }
            }

            foreach (int i in list)
            {
                Console.WriteLine(i);
            }

 

原理 r(n) = (sed + r(n - 1)) % 100;

做法2：先把1-100这100个数按顺序放入数组arr，再重复100次下面的操作，生成两个介于 >=0,<100 之间的随机数m、n，颠倒arr[m]和arr[n]的数。

            int[] arr = new int[100];
            //把100个数顺序放入
            for (int i = 0; i < 100; i++)
            {
                arr[i] = i + 1;
            }
            Random rand = new Random();
            for (int i = 0; i < 2; i++)
            {
                int m = rand.Next(0, 100);
                int n = rand.Next(0, 100);
                if (m != n)
                {
                    int temp = arr[m];
                    arr[m] = arr[n];
                    arr[n] = temp;
                }
                Console.WriteLine(arr[m] + " " + arr[n]);
            }

    string RndNum(int VcodeNum)
        {
            string Vchar = "0,1,2,3,4,5,6,7,8,9";
            string[] VcArray = Vchar.Split(',');
            string VNum = "";
            int temp = -1;//记录上次随机数值，尽量避免产生几个相同的随机数
            Random rand = new Random();
            for (int i = 1; i < VcodeNum+1; i++)
            {
                if(temp!=-1)
                {
                    rand = new Random(i * temp * unchecked((int)DateTime.Now.Ticks));
                }
                int t = rand.Next(VcArray.Length);
                if(temp!=-1&&temp==t)
                {
                    return RndNum(VcodeNum);
                }
                temp = t;
                VNum += VcArray[t];
            }
            return VNum;
        }