该函数接受字符串输入，并删除出现一定次数的所有字符

Question

这里有一个单词"angoora“，'a‘和'o’出现了2次，如果用户输入是2，那么输出应该是"ngr”，函数应该删除a和o，因为它在字符串中出现了2次。如果用户输入3，则输出应为"angoora“，因为没有字符出现3次。

我正在这样做，但我认为这不是一个正确的方式，因为它不会引导我走向我的目标，任何帮助都会非常感谢。

public static SortedDictionary<char, int> Count(string stringToCount)
{
    SortedDictionary<char, int> characterCount = new SortedDictionary<char, int>();

    foreach (var character in stringToCount)
    {
        int counter = 0;
        characterCount.TryGetValue(character, out counter);
        characterCount[character] = counter + 1;
    }

    return characterCount;
}

Answer 1

您可以使用此函数

static string Fix(string item, int count)
{
    var chars = item.ToList().GroupBy(g => g).Select(s => new { Ch = s.Key.ToString(), Count = s.Count() }).Where(w => w.Count < count).ToList();
    var characters = string.Join("", item.ToList().Select(s => s.ToString()).Where(wi => chars.Any(a => a.Ch == wi)).ToList());
    return characters;
}

Answer 2

您可以使用LINQs来查找每个字符出现的次数。然后删除你想要的次数。像这样的东西

public static string RemoveCharactersThatOccurNumberOfTimes(string s, int numberOfOccurances)
{
    var charactersToBeRemoved = s.GroupBy(c => c).Where(g => g.Count() == numberOfOccurances).Select(g => g.Key);
    return String.Join("", s.Where(c => !charactersToBeRemoved.Contains(c)));
}

Answer 3

您的characterCount SortedDictionary为空。

目前您正在执行以下操作：

public static SortedDictionary<char, int> Count(string stringToCount)
{
    // Create a new empty SortedDictionary
     SortedDictionary<char, int> characterCount = new SortedDictionary<char, int>();

    // Loop through each character in stringToCount and see if SortedDictionary contains a key equal to this character (it doesn't as dictionary is empty).
    foreach (var character in stringToCount)
     {
         int counter = 0;
         characterCount.TryGetValue(character, out counter);
         characterCount[character] = counter +1;
     }

     return characterCount;
}

你肯定想要这样的东西：

public static SortedDictionary<char, int> Count(string stringToCount)
{
    // Create a new empty SortedDictionary (use var keyword if defining variables)
    var characterCount = new SortedDictionary<char, int>();

    // Loop through each character and add to dictionary
    foreach (var character in stringToCount)
    {
        // If character already in SortedDictionary.
        if (characterCount.TryGetValue(character, out int count))
        {
            // Increment count value.
            characterCount[character] = count + 1;
            // Above line can also be: ++characterCount[character];
        }
        // Else, character not already in dictionary.
        else
        {
            // Add character in dictionary and set count to 1.
            characterCount.Add(character, 1);
        }
    }

    return characterCount;
}