Is it possible to combine a list of words in C# like this?

I want to create an array like this

Array Input: {A, B, C}
Output: {A, B, C}, {AB, C}, {A, BC}, {ABC}

Array Input: {A, B, C, D}
Output: {A, B, C, D}, {AB, C, D}, {ABC, D}, {AB, CD}, {ABCD}, {A, BC, D}, {A, BCD}, {A B CD}

I was thinking about making it in C#, but I haven’t been able to solve it yet.

Can you code this algorithm?

>Solution :

Yes, in general case you can encode each possible split as 0 or 1 (true or false) to have all the combinations:

  A     B     C    D
     ^     ^     ^
  0 or 1  ...  0 or 1    

For instance:

  ABCD    - 000 (no splits)
  A,BCD   - 100 (split, then no splits)
  AB,CD   - 010 
  ABC,D   - 001
  AB,C,D  - 011
  A,B,CD  - 110
  ...
  A,B,C,D - 111 (all splits)        

Code:

private static IEnumerable<List<List<T>>> MySolution<T>(IEnumerable<T> source) {
  if (source is null)
    throw new ArgumentNullException(nameof(source));

  var array = source.ToArray();

  if (array.Length <= 0)
    yield break;

  for (int mask = 0; mask < 1 << (array.Length - 1); ++mask) {
    List<List<T>> result = new List<List<T>>();

    result.Add(new List<T>() { array[0] });

    for (int index = 0; index < array.Length - 1; ++index) {
      if ((mask & (1 << index)) != 0)
        result.Add(new List<T>() { });

      result[result.Count - 1].Add(array[index + 1]);
    }

    yield return result;
  }
}

Demo:

  char[] demo = new char[] { 'A', 'B', 'C', 'D' };

  var result = MySolution(demo)
    .Select(rec => "{" + string.Join(", ", rec
      .Select(item => string.Join("", item))) + "}");

  Console.WriteLine(string.Join(Environment.NewLine, result));

Output:

{ABCD}
{A, BCD}
{AB, CD}
{A, B, CD}
{ABC, D}
{A, BC, D}
{AB, C, D}
{A, B, C, D}