Question

System.Random generator = new Random(DateTime.Now.Millisecond);
int[] lotteryNumber = new int[7];

Console.WriteLine("Your lottery numbers: ");
for (int i = 0; i<7; i++)
{
    lotteryNumber[i] = generator.Next(1, 37);
    Console.Write("{0} ",lotteryNumber[i]);
}
Console.ReadLine();

我需要制作一个打印7个彩票号码的程序，但不需要重复。上面的代码打印了（1-37）范围内的7个随机数，但重复了appaer。我需要一种方法来防止出现重复的数字。

Answer 1

最简单的方法IMO将生成一系列所有可能的数字（即1-37），对集合进行洗牌，然后取得前七个结果。

在Stack Overflow上搜索“Fisher-Yates shuffle C＃”会找到很多例子。

事实上，您可以修改Fisher-Yates shuffle以在获取结果时产生结果，因此您可以编写如下方法：

var numbers = Enumerable.Range(1, 37).Shuffle().Take(7).ToList();

Answer 2

您可以使用字典但请确保防止重复键插入。字典的键将作为您需要的唯一数字

Answer 3

你可以将它们扔进HashSet<int>。如果您Add并且它返回false，则生成一个新数字。

Answer 4

如果你试图从范围内选择数字而不重复，你需要创建一个包含所有可能数字的数组，然后“随机”选择一个随机选择：

int[] allPossibleNumbers = Enumerable.Range(1, 37).ToArray();
int[] lotteryNumber = new int[7];
for (int i = 0; i < 7; i++)
{
    int index = r.Next(i, 37);
    lotteryNumber[i] = allPossibleNumbers[index];
    allPossibleNumbers[index] = allPossibleNumbers[i];
    // This step not necessary, but allows you to reuse allPossibleNumbers
    // rather than generating a fresh one every time.
    // allPossibleNumbers[i] = lotteryNumber[i];
}

Answer 5

生成包含37个项目的列表。然后在您的for中，选择一个并删除所选的

Answer 6

也许这可能会有所帮助，如果您获得现有数字，只需尝试找到不在数组中的新数字：

static void Main(string[] args)
        {
            System.Random generator = new Random(DateTime.Now.Millisecond); int[] lotteryNumber = new int[7];

            Console.WriteLine("Your lottery numbers: ");
            for (int i = 0; i < 7; i++)
            {
                int lNumber = 0;
                do
                {
                    lNumber = generator.Next(1, 37);
                }
                while (lotteryNumber.Contains(lNumber));
                lotteryNumber[i] = lNumber;

                Console.Write("{0} ", lotteryNumber[i]);
            }
            Console.ReadLine();
        }

Answer 7

HashSet<int> set = new HashSet<int>();
System.Random generator = new Random(DateTime.Now.Millisecond);

while(set.Count < 7){
    set.Add(generator.Next(1,37);
}

这应该可行，因为HashSet会自动忽略重复项。只需循环直到该集合达到您需要的单位数。只有潜在的问题是它有潜在的（不太可能）循环很长一段时间，但它最终应该响应。

Answer 8

所以我拿了你的原始代码......发现了一些逻辑错误并添加了你想要的修复，以防止随机数重复。

享受！

 System.Random generator = new Random(DateTime.Now.Millisecond);
            int[] lotteryNumber = new int[7];
            int lowerBounds = 1;
            int upperBounds = 8;
            int maxNumberLotteryValues = 7;

            if ( ( upperBounds - lowerBounds ) < (maxNumberLotteryValues))
            {
                Console.Write("Warning: Adjust your upper and lower bounds...there are not enough values to create a unique set of Lottery numbers! ");

            }
            else
            {
                Console.WriteLine("Your lottery numbers: ");
                for (int i = 0; i < maxNumberLotteryValues; i++)
                {
                    int nextNumber = generator.Next(lowerBounds, upperBounds);
                    int count = lowerBounds;  //Prevent infinite loop

                    while ((lotteryNumber.Contains(nextNumber))
                        && (count <= upperBounds))
                    {
                        nextNumber = generator.Next(lowerBounds, upperBounds);
                        count++;  //Prevent infinite loop
                    }

                    lotteryNumber[i] = nextNumber;
                    Console.Write("{0} ", lotteryNumber[i]);
                }
            }

            Console.ReadLine();

Answer 9

const int nBalls = 37;
const int nPicks = 6;
int[] balls = new int[nPicks];
Random rnd = new Random(DateTime.Now.Millisecond);

int remainingBalls=nBalls;
int remainingPicks=nPicks;
for (int i = 1; i <= nBalls; i++)
{
    if (rnd.Next(1, remainingBalls+1) <= remainingPicks)
        balls[--remainingPicks]=i;
    remainingBalls--;
}

Console.WriteLine(string.Join(",",balls));

随着nPicks / nBalls变大，将超越Shuffle和HashSet方法。

避免随机重复

9 个答案: