Question

我正在尝试将字符串元素随机化，但是我的代码正在重复字符串。有人可以解释我的代码有什么问题吗？

string[] words = Console.ReadLine().Split();
//input = "Welcome and have fun learning programming"

Random number = new Random();

for (int i = 0; i < words.Length; i++)
{
    int currRandomNumber = number.Next(0, words.Length);
    words[i] = words[currRandomNumber];
}

Console.WriteLine(string.Join(' ', words));      
//output = "have learning learning learning learning programming"

我遇到重复单词的问题，它不是随机的吗？如果您不明白我的意思，请参阅我在代码中添加的注释。任何帮助将不胜感激！

Answer 1

重复这些单词是因为您正在这样做：

words[i] = words[currRandomNumber];

该行的意思是“将索引currRandomNumber上的单词复制到索引i”。只要i和currRandomNumber不同，就可以保证您有一个重复的单词。

您想做的可能是交换 currRandomNumber和i上的单词：

var temp = words[i];
words[i] = words[currRandomNumber];
words[currRandomNumber] = temp;
// in C# 7, you could swap two values very easily by:
// (words[currRandomNumber], words[i]) = (words[i], words[currRandomNumber]);

或者，您可以使用Fisher Yates shuffling algorithm，以确保每个排列出现的机会均等：

static void Shuffle<T>(T[] array)
{
    int n = array.Length;
    for (int i = 0; i < n; i++)
    {
        int r = i + _random.Next(n - i);
        T t = array[r];
        array[r] = array[i];
        array[i] = t;
    }
}

// Shuffle(words);

Answer 2

或者，您可以将每个单词以随机顺序放入新列表中：

    List<string> words = Console.ReadLine().Split().ToList();
    //input = "Welcome and have fun learning programming"

    Random number = new Random();
    var newwords = new List<string> ();

    while (words.Count > 0)
    {
        int currRandomNumber = number.Next(0, words.Count);
        newwords.Add( words[currRandomNumber]);
        words.RemoveAt(currRandomNumber);
    }

    Console.WriteLine(string.Join(' ', newwords));

在C＃

2 个答案: