Question

I have a list of objects

public class foo
{
    public decimal val1 {get;set;}
    public decimal val2 {get;set;}
}

I val1 and val2 can contain both negative or positive values.
if I have a List<foo>items is there a clean way I can sort them so that a negative value in either val1 or val2 are not the first or last item in the list.

My list size can very from 1 – 100. if it is less then 3 I do not need to sort. But if it is >= 3 I need to make sure any negative values are not first or last in the list.

Answer 1

You would try to push a “positive” value to the head and the tail of the list if they exist:

if (myList.Count > 2)
{
    //push a positive to the head of the list
    var firstPositive = myList.FirstOrDefault(x => x.val1 > 0 && x.val2 > 0);
    if (firstPositive != null)
    {
        myList.Remove(firstPositive);
        myList.Insert(0, firstPositive);
    }

    //push a positive to the tail of the list
    var secondPositive = myList.Skip(1).FirstOrDefault(x => x.val1 > 0 && x.val2 > 0);
    if (secondPositive != null)
    {
        myList.Remove(secondPositive);
        myList.Add(secondPositive);
    }
}