Delete duplicates in a List of int arrays

Question

having a List of int arrays like:

List intArrList = new List();
intArrList.Add(new int[3] { 0, 0, 0 });
intArrList.Add(new int[5] {         


        

Answer 1

Use GroupBy:

var result = intArrList.GroupBy(c => String.Join(",", c))
                       .Select(c => c.First().ToList()).ToList();

The result:

{0, 0, 0}

{20, 30, 10, 4, 6}

{1, 2, 5}

{12, 22, 54}

{1, 2, 6, 7, 8}

{0, 0, 0, 0}

EDIT: If you want to consider {1,2,3,4} be equal to {2,3,4,1} you need to use OrderBy like this:

var result = intArrList.GroupBy(p => string.Join(", ", p.OrderBy(c => c)))
                       .Select(c => c.First().ToList()).ToList(); 

EDIT2: To help understanding how the LINQ GroupBy solution works consider the following method:

public List FindDistinctWithoutLinq(List lst)
{
    var dic = new Dictionary();
    foreach (var item in lst)
    {
        string key = string.Join(",", item.OrderBy(c=>c));

        if (!dic.ContainsKey(key))
        {
            dic.Add(key, item);
        }
    }

    return dic.Values.ToList();
}