C# >我认为这就是问题所在。 char[] partialWord = word.ToCharArray(); int numberOfCharsToHide = word.Length / 2; //divide word

>我认为这就是问题所在。

    char[] partialWord = word.ToCharArray();

    int numberOfCharsToHide = word.Length / 2;          //divide word length by 2 to get chars to hide 
    Random randomNumberGenerator = new Random();        //generate rand number
    HashSet<int> maskedIndices = new HashSet<int>();    //This is to make sure that I select unique indices to hide. Hashset helps in achieving this
    for (int i = 0; i < numberOfCharsToHide; i++)       //counter until it reaches words to hide
    {
        int rIndex = randomNumberGenerator.Next(0, word.Length);       //init rindex
        while (!maskedIndices.Add(rIndex))
        {
            rIndex = randomNumberGenerator.Next(0, word.Length); //This is to make sure that I select unique indices to hide. Hashset helps in achieving this
        }
        partialWord[rIndex] = '_';                      //replace with _
    }
    return new string(partialWord);   

var builder = new StringBuilder(word);
for (int i = 0 ; i < word.Length ; i++) {
    builder.Insert(i * 2, " ");
}
return builder.ToString().TrimStart(' '); // TrimStart is called here to remove the leading whitespace. If you want to keep it, delete the call.

// char[] partialWord  is used from question code
char[] result = new char[(partialWord.Length * 2) - 1];
for(int i = 0; i < result.Length; i++)
{
    result[i] = i % 2 == 0 ? partialWord[i / 2] : ' ';
}
return new string(result);