Question

I have a list with some values, lets say 1 2 3 4 5 6

I need to pair them up like this:
12 13 14 15 16 23 24 25 26 34 35 36 45 46 56

Basically, I need to mix them all up to create unique sets of values.

Do you have any ideas on how to create a new list like this?

Thank you for your input!

Answer 1

For the data from your sample you can do it with a trivial pair of nested loops:

var list = new List<int>{1,2,3,4,5,6};
var res = new List<int>();
for (int i = 0 ; i != list.Count ; i++) {
    for (int j = i+1 ; j != list.Count ; j++) {
        res.Add(list[i]*10+list[j]);
    }
}

For more complex data, you can use a string concatenation trick:

var list = new List<int>{98,76,54,32,10};
var res = new List<int>();
for (int i = 0 ; i != list.Count ; i++) {
    for (int j = i+1 ; j != list.Count ; j++) {
        res.Add(int.Parse(string.Format("{0}{1}", list[i], list[j])));
    }
}