C#一个算法题

Question

已知一个字符串，如“djsdfkdkfdkfj”，求出字符串中有多少种字符，以及每种字符的个数。
用c#编写，用数组实现。希望大家各显神通，多写出几种算法来

Answer 1

            String str = "djsdfkdkfdkfj";            List<Char> listC = new List<Char>();
            List<Int32> listN = new List<Int32>();            for (Int32 i = 0; i < str.Length; i++)
            {
                Char c = str[i];                if (listC.Contains(c))
                {
                    Int32 index = listC.IndexOf(c);
                    listN[index] = listN[index] + 1;
                }
                else
                {
                    listC.Add(c);
                    listN.Add(1);
                }
            }            for (Int32 j = 0; j < listC.Count; j++)
            {
                Console.WriteLine(listC[j] + " : " + listN[j]);
            }

Answer 2

string str="djsdfkdkfdkfj";
while(str.length>0)
{  
string s=str.substring(1,1);
console.Writtline("字符{0}有{1}个",s,str.length-str.replace(s,"").length);
str=str.replace(s,"");
}手写的

Answer 3

//经测试通过，但没用数组，用的是Dictionary
string str = "djsdfkdkfdkfj";
Dictionary<char, int> freq = new Dictionary<char, int>();
while (str.Length > 0)
{
char ch = str[0];
string s = str.Replace(ch.ToString(), string.Empty);
freq.Add(ch, str.Length - s.Length);
str = s;
}

Answer 4

[code]
    [Test]
    public void Test1()
    {
      String str = "djsdfkdkfdkfj";
      var lu = (from c in str
                select c).GroupBy(c => c);
      Console.WriteLine(lu.Count());
      foreach (var l in lu)
      {
        Console.WriteLine("{0} : {1}", l.Key, l.Count());
      }
    }
[/code]

Answer 5

    [Test]
    public void Test1()
    {
      String str = "djsdfkdkfdkfj";
      var lu = (from c in str
                select c).GroupBy(c => c);
      Console.WriteLine(lu.Count());
      foreach (var l in lu)
      {
        Console.WriteLine("{0} : {1}", l.Key, l.Count());
      }
    }