Combination of List<List<int>>

Question

I've a List of this type List> that contains this

List<int> A = new List<int> {1, 2, 3, 4, 5}; List<int> B = new List<int> {0, 1}; List<int> C = new List<int> {6}; List<int> X = new List<int> {....,....}; 

I want to have all combinations like this

1-0-6 1-1-6 2-0-6 2-1-6 3-0-6 

and so on.

According to you is This possibile to resolve using Linq?

Answer 1

It's quite similar to this answer I gave to another question:

var combinations = from a in A                    from b in B                    from c in C                    orderby a, b, c                    select new List<int> { a, b, c };  var x = combinations.ToList(); 

For a variable number of inputs, now with added generics:

var x = AllCombinationsOf(A, B, C);  public static List<List<T>> AllCombinationsOf<T>(params List<T>[] sets) {     // need array bounds checking etc for production     var combinations = new List<List<T>>();      // prime the data     foreach (var value in sets[0])         combinations.Add(new List<T> { value });      foreach (var set in sets.Skip(1))         combinations = AddExtraSet(combinations, set);      return combinations; }  private static List<List<T>> AddExtraSet<T>      (List<List<T>> combinations, List<T> set) {     var newCombinations = from value in set                           from combination in combinations                           select new List<T>(combination) { value };      return newCombinations.ToList(); } 

Answer 2

If the number of dimensions is fixed, this is simply SelectMany:

var qry = from a in A           from b in B           from c in C           select new {A=a,B=b,C=c}; 

However, if the number of dimensions is controlled by the data, you need to use recursion:

static void Main() {     List<List<int>> outerList = new List<List<int>>     {   new List<int>(){1, 2, 3, 4, 5},         new List<int>(){0, 1},         new List<int>(){6,3},         new List<int>(){1,3,5}     };     int[] result = new int[outerList.Count];     Recurse(result, 0, outerList); } static void Recurse<TList>(int[] selected, int index,     IEnumerable<TList> remaining) where TList : IEnumerable<int> {     IEnumerable<int> nextList = remaining.FirstOrDefault();     if (nextList == null) {         StringBuilder sb = new StringBuilder();         foreach (int i in selected) {             sb.Append(i).Append(',');         }         if (sb.Length > 0) sb.Length--;         Console.WriteLine(sb);     } else {         foreach (int i in nextList) {             selected[index] = i;             Recurse(selected, index + 1, remaining.Skip(1));         }     } }