Giomuti Giomuti - 1 year ago 65
C# Question

Combination of List<List<int>>

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


and so on.

According to you is This possibile to resolve using Linq?

Answer Source

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();