I have a List of Items and a List of ItemsContainer which is a class that holds items.

1. all the items are unique
2. every item is located in at most one ItemContainer
3. the ItemContainer support only: Remove(Item) and Contains(Item) methods

I would like to remove all the items in my list from all the itemContainers.

right now I'm thinking of doing something like that:

    List<ItemContainer> itemContainerList = ...
    List<Item> itemsList = ...

          
foreach (ItemContainer itemContainer in itemContainerList)
            {
                foreach (Item item in itemsList)
                {
                    if (itemContainer.Contains(item))
                    {
                        itemContainer.Remove(item);
                    }
                }
            }

Hoping to make this more efficient and elegant.

Thanks, Aviram.

CodePudding user response：

Following on from further information being unveiled, I've found that the constraints mean that any of the "conventionally efficient" ways of doing it aren't applicable.

Based on your constraints, I can only suggest flipping the loops:

foreach (Item item in itemsList)
{
    foreach (ItemContainer itemContainer in itemContainerList)
    {
        if (itemContainer.Contains(item))
        {
            itemContainer.Remove(item);
            break;
        }
    }
}

It's still not ideal, due to the unfortunate prior existing issues of your set-up, but it'll be slightly quicker by virtue of only going through the items once.

CodePudding user response：

You can use .RemoveAll() with .Any(),

var removedItemCount = itemContainerList
           .RemoveAll(itemContainer => itemsList
           .Any(item => itemContainer.Contains(item)));