print with incremental order all combinations of string without repetition

Question

I have a string

to do so I am doing:

    string[] combinations = Combinations("LEQN");
    foreach (string s in combinations)
    {
        Console.WriteLine(s);
    }

and method Combinations:

public static string[] Combinations(string str)
         {
            if (string.IsNullOrEmpty(str))  throw new ArgumentException("Invalid input");
            if (str.Length == 1)            return new string[] { str };
            // read the last character
            char c = str[str.Length - 1];
            // apart from the last character send remaining string for further processing
            string[] returnArray = Combinations(str.Substring(0, str.Length - 1));
            // List to keep final string combinations
            List<string> finalArray = new List<string>();
            // add whatever is coming from the previous routine
            foreach (string s in returnArray)
                finalArray.Add(s);
            // take the last character
            finalArray.Add(c.ToString());
            // take the combination between the last char and the returning strings from the previous routine
            foreach (string s in returnArray)
                finalArray.Add(s + c);

            return finalArray.ToArray();
        }

this would print:

L
E
LE
Q
LQ
EQ
LEQ
N
LN
EN
LEN
QN
LQN
EQN
LEQN

which is correct, however I woul like to get result like

L   N   Q   E   LN  NQ  EL  QE  LNQ ELN QEL NQE NQEL

How to accomplish that?

Answer 1

You can sort based on string length using LINQ OrderBy

foreach (string s in combinations.OrderBy(str => str.Length))
{
    Console.WriteLine(s);
}