如何创建非重复随机数数组

Question

我在 C# 中有一个彩票应用程序，它接收要绘制的数字数量以及要绘制的最大数量。我已经编码以创建一个包含所需随机数的数组，但我需要它们是唯一的，并且在执行时遇到问题.如果有人能给我一些建议，我将不胜感激，谢谢

到目前为止，这是我的代码：

class Lottery

{

  static int[] numberHolder; //array to be filled with numbers up to an 
                             //amount entered by the user eg 42 Max

  static int[] drawHolder;   //array to hold the each random number 
                             //drawn from the pool of numbers eg 7 numbers

    public Lottery() //Lottery class Constructor
    {

    }


    //method which takes in a number limit and amount of numbers to be drawn
    public String drawNumbers(int numLimit, int numAmount) 
    {

        Random RandomNumber = new Random();

        for (int i = 0; i < numLimit ; i++) //loop to fill up numberHolder array
                                            // with predefined limit of numbers

        {
            numberHolder[i] = i++;
        }

        for (int i = 0; i < numAmount; i++)
        {


            // code to pick unique random numbers no greater than numAmount 
            // and add them to the drawHolder[] array
            drawHolder[i] = RandomNumber.Next(1, numLimit);

        }





        //return the drawHolder array to String
        return null;
    }





}

Answer 1

在我看来，你应该改变你的方法。

与其考虑“我将生成随机索引来选择我的数字”，您必须确保没有任何重复项，我会简单地洗牌数组并首先取您需要的 X。 这样，您就不必担心索引或重复项。

所以你的第二个 for 循环将更改为

drawHolder = numberHolder.OrderBy(x => new Guid()).Take(numAmount);

（请注意，我使用了new Guid()因此您可以删除您的RandomNumber声明行。如前所述，GUID 是一个唯一值，不打算用作随机代。您也可以使用x => RandomNumber.Next() ，但如果你真的需要一个强大而可靠的 shuffle，请阅读Fisher-Yates ）

您还可以用简单的Enumerable.Range替换 numberHolder 数组

所以你的整个代码会变成（请注意我已经改变了你的方法名称以使用 C# 约定，方法名称应该在 PascalCase 中）

public string DrawNumbers(int numLimit, int numAmount) 
{
    drawHolder = Enumerable.Range(0, numLimit).OrderBy(x => new Guid()).Take(numAmount);

    return string.Join(", ", drawHolder);
} 

Answer 2

听起来像改组数组比生成随机数更好。 你可以这样做：

int[] ShuffleArray(int[] array)
{
  Random r = new Random();
  for (int i = array.Length; i > 0; i--)
  {
    int j = r.Next(i);
    int k = array[j];
    array[j] = array[i - 1];
    array[i - 1]  = k;
  }
  return array;
}

归功于@RohitArora 。

Answer 3

有几个选项，您可以使用Contains方法。

numberHolder.Contains(value)

Any() 方法。

numberHolder.Any(x=>x == value);

Answer 4

这可以使用非重复整数数组的改组算法轻松实现：

public int[] GenerateNonRepeatingNumbers(int seed, int min, int range)
    {
        // Make sure range is an appropriate value
        if (range <= 0)
        {
            throw new ArgumentException("Range must be greater than zero.");
        }

        // Make an array to hold our numbers
        int[] numbers = new int[range];

        // Seed the RNG.
        Random rng = new Random(seed);

        // Fill the array with all numbers from min to min + range
        for (int i = 0; i < range; numbers[i] = min + i++) { }

        int
            a = 0, // Swap index
            t = 0; // Temporary value storage

        // Scramble the values
        for (int i = 0; i < range; i++)
        {
            // Get a random index that isn't i
            while ((a = rng.Next(range)) == i) { };
            // Store the old value at i
            t = numbers[i]; 
            // Change the old value to the value at the random index
            numbers[i] = numbers[a]; 
            // Set value at random index to our old value from numbers[i]
            numbers[a] = t; 
        }

        return numbers;
    }

Answer 5

我会像这样使用Enumerable.Distinct ：

public String drawNumbers(int numLimit, int numAmount) {
    var numbers = Infinite(() => random.Next(numLimit)).Distinct().Take(numAmount);
    return string.Join(" ", numbers);
}
private Random random = new Random();
private static IEnumerable<T> Infinite<T>(Func<T> generator) {
    while (true) yield return generator();
}

在大多数numLimit较大且numAmount为 10 或更小的彩票中，此方法比创建和改组长度为numLimit的数组更有效。

如果涉及真钱，您应该使用比Random或Guid更好的随机性生成器。 这是一个完整的Lottery类，它使用加密随机数生成器（基于 Microsoft 的RNGCryptoServiceProvider ）。

class Lottery
{
    // Use Random if this is in a school project or toy application
    // private Random randomGenerator = new Random();

    // Use CryptoRandom if you're dealing with real money or prizes
    private CryptoRandom randomGenerator = new CryptoRandom();

    //method which takes in a number limit and amount of numbers to be drawn
    public String drawNumbers(int numLimit, int numAmount) 
    {
        return drawNumbers(1, numLimit, numAmount);
    }

    // takes the minimum and maximum lottery numbers and how many numbers to draw
    public String drawNumbers(int minNumber, int maxNumber, int count)
    {
        if (maxNumber < minNumber) return string.Empty;
        int maxCount = (int)Math.Min(int.MaxValue, 1L + maxNumber - minNumber);
        if (count > maxCount) count = maxCount;
        if (count < 1) return string.Empty;
        var numbers = Infinite(() => randomGenerator.Next(minNumber, maxNumber)).Distinct().Take(count);
        return string.Join(" ", numbers);
    }

    private static IEnumerable<T> Infinite<T>(Func<T> generator)
    {
        while (true)
            yield return generator();
    }

    private class CryptoRandom
    {
        private readonly RNGCryptoServiceProvider _rng = new RNGCryptoServiceProvider();
        private readonly byte[] _uint32Buffer = new byte[4];
        public int Next(int minValue, int maxValue)
        {
            if (minValue == maxValue) return minValue;
            long diff = (long)maxValue - minValue;
            const long Max = 1L + uint.MaxValue;
            long randLimit = Max - (Max % diff);
            uint rand;
            do {
                _rng.GetBytes(_uint32Buffer);
                rand = BitConverter.ToUInt32(_uint32Buffer, 0);
            } while (rand >= randLimit);
            return (int)(minValue + (rand % diff));
        }
    }
}

Answer 6

为时已晚，但我使用了我创建的名为 M_Randomizer 的方法。

using System;
class Randomizer
{
    public int[] M_Randomizer(int x)
    {
        bool b = false;
        if (x < -1)
        {
            b = true;
            x = -1 * x;
        }
        if(x == -1)
            x = 0;
        if (x < 2)
            return new int[x];

        int[] site;
        int k = new Random(Guid.NewGuid().GetHashCode()).Next() % 2;
        if (x == 2)
        {
            site = new int[2];
            site[0] = k;
            site[1] = 1 - site[0];
            return site;
        }
        else if (x == 3)
        {
            site = new int[3];
            site[0] = new Random(Guid.NewGuid().GetHashCode()).Next(0, 3);
            site[1] = (site[0] + k + 1) % 3;
            site[2] = 3 - (site[0] + site[1]);
            return site;
        }
        site = new int[x];
        int a = 0, m = 0, n = 0, tmp = 0;
        int[] p = M_Randomizer(3);
        int[] q;

        if (x % 3 == 0)
            q = M_Randomizer(x / 3);
        else
            q = M_Randomizer((x / 3) + 1);
        if (k == 0)
        {
            for (m = 0; m < q.Length; m++)
            {
                for (n = 0; n < p.Length && a < x; n++)
                {
                    tmp = (q[m] * 3) + p[n];
                    if (tmp < x)
                    {
                        site[a] = tmp;
                        a++;
                    }
                }
            }
        }
        else
        {
            while (n < p.Length)
            {
                while (a < x)
                {
                    tmp = (q[m] * 3) + p[n];
                    if (tmp < x)
                    {
                        site[a] = tmp;
                        a++;
                    }
                    m = m + k;
                    if (m >= q.Length)
                        break;
                }
                m = m % q.Length;
                n++;
            }
        }

        a = (new Random(Guid.NewGuid().GetHashCode()).Next() % 2) + 1;
        k = new Random(Guid.NewGuid().GetHashCode()).Next() % 10;
        if (k > 5)
            for (int i = a; i < k; i++)
                while (a < site.Length)
                {
                    if (k % (a + 1) == 0)
                    {
                        tmp = site[a - 1];
                        site[a - 1] = site[a];
                        site[a] = tmp;
                    }
                    a = a + 2;
                }

        k = new Random(Guid.NewGuid().GetHashCode()).Next() % 10;
        if (k > 5)
        {
            n = x / 2;
            k = 0;
            if (x % 2 != 0)
                k = (new Random(Guid.NewGuid().GetHashCode()).Next() % 2);

            p = new int[n + k];
            m = (x - n) - k;
            for (a = 0; m < x; a++, m++)
                p[a] = site[m];

            m = n + k;
            for (a = (x - m) - 1; a >= 0; a--, m++)
                site[m] = site[a];

            for (a = 0; a < p.Length; a++)
                site[a] = p[a];
        }

        int[] site2;
        int[] site3 = new int[x];
        if (b)
            return site;
        else
            site2 = M_Randomizer(-1 * x);

        for (a = 0; a < site.Length; a++)
            site3[site2[a]] = site[a];

        return site3;
    }

    public int[] M_Randomizer(int x, int start)
    {
        int[] dm = M_Randomizer(x);

        for(int a = 0; a < x; a++)
            dm[a] = dm[a] + start;

        return dm;
    }
}

Answer 7

不确定这是最快的方法，但我想出了这个解决方案：

public int[] GetRandomNumber(int from, int to)
{
    Random r = new Random();

    List<KeyValuePair<int, int>> numbers = new List<KeyValuePair<int, int>>();
    for(int n = from; n <= to; n++)
    {
        numbers.Add(new KeyValuePair<int, int>(r.Next(1, int.MaxValue), n));
    }

    return numbers.OrderBy(o => o.Key).Select(i => i.Value).ToArray();
}

Answer 8

我会保持简单：

private Random _rnd = new Random();
public String drawNumbers(int numLimit, int numAmount) 
{
    return String.Join("," ,
        Enumerable
            .Range(1, numLimit)
            .OrderBy(x => _rnd.Next())
            .Take(numAmount));
}

将Random实例的声明保留在方法之外，以防止在快速连续调用该方法时返回相同的序列。

Answer 9

有很多方法可以做到这一点。 您可以对if array[i] == array[i+1]进行排序然后进行比较。