怎么样取数组的中不重复的元素呢？

Question

怎么样取数组的中不重复的元素呢？
一个string数组，我要取4次，如何取才能取出不重复的元素呢？

Answer 1

一点技术含量都没有...
str.GroupBy(c => c).Select(s => s.Key).OrderBy(k => Guid.NewGuid()).Take(4).ToList().ForEach((c) =>{ Console.WriteLine(c); });

Answer 2

private  string NewMethod( string [] s)
        {
          //  string[] s = new string[] { "5", "2", "5", "8", "8", "1", "1" };            List<string> L = new List<string>();            for (int j = 0; j < s.Length; j++)
            {
                bool f = false;
                L.Clear();
                L.Add(s[j]);
                for (int i = j + 1; i < s.Length; i++)
                {
                    if (!L.Contains(s[i]))
                    {
                        L.Add(s[i]);
                        if (L.Count == 4)
                        {
                            f = true;
                            break;
                        }
                    }                }
                if (f)
                {
                    break;
                }
            }
            string sr =null;
            if (L.Count != 4)
                return null;
            foreach (string ss in L)
                sr = sr + ss;
            return sr;
        }

Answer 3

private  string [] NewMethod( string [] s)
        {
          //  string[] s = new string[] { "5", "2", "5", "8", "8", "1", "1" };            List<string> L = new List<string>();            for (int j = 0; j < s.Length; j++)
            {
                bool f = false;
                L.Clear();
                L.Add(s[j]);
                for (int i = j + 1; i < s.Length; i++)
                {
                    if (!L.Contains(s[i]))
                    {
                        L.Add(s[i]);
                        if (L.Count == 4)
                        {
                            f = true;
                            break;
                        }
                    }                }
                if (f)
                {
                    break;
                }
            }
            string sr = "";
            if (L.Count != 4)
                return null;
            foreach (string ss in L)
                sr = sr + ss+",";
            return sr.Trim(',').Split(',');
        }

Answer 4

 private  string [] NewMethod( string [] s,int n)//取n个
        {
          //  string[] s = new string[] { "5", "2", "5", "8", "8", "1", "1" };            List<string> L = new List<string>();            for (int j = 0; j < s.Length; j++)
            {
                bool f = false;
                L.Clear();
                L.Add(s[j]);
                for (int i = j + 1; i < s.Length; i++)
                {
                    if (!L.Contains(s[i]))
                    {
                        L.Add(s[i]);
                        if (L.Count == n)
                        {
                            f = true;
                            break;
                        }
                    }                }
                if (f)
                {
                    break;
                }
            }
            string sr = "";
            if (L.Count != n)
                return null;
            foreach (string ss in L)
                sr = sr + ss+",";
            return sr.Trim(',').Split(',');
        }