随机打乱数组最简洁高效的方法！
例如 

string str = "abcdefghijklmn";

把这个字符串中的字符顺序打乱，越随机越好


------解决方案--------------------
string str = "abcdefghijklmn";
Random r = new Random();
var q = from c in str orderby r.Next() select c;
Console.Write(new string(q.ToArray()));