Question

Whenever I want to insert into a SortedList, I check to see if the item exists, then I insert. Is this performing the same search twice? Once to see if the item is there and again to find where to insert the item? Is there a way to optimize this to speed it up or is this just the way to do it, no changes necessary?

if( sortedList.ContainsKey( foo ) == false ){
    sortedList.Add( foo, 0 );
}

Answer 1

You can add the items to a HashSet and the List, searching in the hash set is the fastest way to see if you have to add the value to the list.

if( hashSet.Contains( foo ) == false ){
    sortedList.Add( foo, 0 );  
    hashSet.Add(foo);
}