Question

I have two list : (Note: List’s Items are combination of “NAME” & “ID” )

List<string> ListA = new List() {"SAM001","SAM002","SAM003","PIT001","PIT002","PIT004","ROSE001","ROSE002","JASE001" };
//so on

List<string> ListB = new List() {"SAM001","SAM003","PIT000","ROSE002","JASE001","INDI000"};` 
//so on...

Now Based on these two list i want to create two new list suppose listCommon & listUncommon.

listCommon will contain all matched items of ListA & ListB.

listUnCommon will contain all remaining items of ListA

Now My condition is if Any item in ListB has NAME + 000 then all the items of ListA starting with that Name should add in my listCommon.

Example 1 : if ListB item is PIT000 and ListA item are PIT001,PIT002,PIT003,ABC001
then listCommon = PIT001,PIT002,PIT003 because ListB has PIT with 000 so condition true all ListA ‘PIT’ items added in listcommon

So as above list and my condition i want my final list below

List<string> listCommon = new List() {"SAM001","SAM003", "PIT001","PIT002","PIT004","ROSE002", "JASE001" };
List<string> listUncommon = new List() {"SAM002", "ROSE001"};

Please suggest..i just spend my couple of minutes in loops but not getting actual result as i mentioned 🙁

Answer 1

This should work.

var common = ListA.Intersect(ListB)
    .Concat(
        ListA.Where(a => 
             ListB.Any(
                b => b.EndsWith("000") && 
                b.StartsWith(a.Substring(0, a.Length - 3))
             )
        )
    );
var uncommon = ListA.Except(common);

Using an insersect, then you are selecting any from list A where list B has an entry that matches the first 3 letters and ends with 000.

This is not the most efficient way of doing this, however it is terse code-wise.