.net - Best algorithm for synchronizing two IList in C# 2.0

Question

Imagine the following type:

public struct Account
{
    public int Id;
    public double Amount;
}

What is the best algorithm to synchronize two IList<Account> in C# 2.0 ? (No linq) ?

The first list (L1) is the reference list, the second (L2) is the one to synchronize according to the first:

• All accounts in L2 that are no longer present in L1 must be deleted from L2
• All accounts in L2 that still exist in L1 must be updated (amount attribute)
• All accounts that are in L1 but not yet in L2 must be added to L2

The Id identifies accounts. It's no too hard to find a naive and working algorithm, but I would like to know if there is a smart solution to handle this scenario without ruining readability and perfs.

EDIT :

• Account type doesn't matter, is could be a class, has properties, equality members, etc.
• L1 and L2 are not sorted
• L2 items could not be replaced by L1 items, they must be updated (field by field, property by property)

Answer 1

For a start I'd get rid of the mutable struct. Mutable value types are a fundamentally bad thing. (As are public fields, IMO.)

It's probably worth building a Dictionary so you can easily compare the contents of the two lists. Once you've got that easy way of checking for presence/absence, the rest should be straightforward.

To be honest though, it sounds like you basically want L2 to be a complete copy of L1... clear L2 and just call AddRange? Or is the point that you also want to take other actions while you're changing L2?