Quickly searching a doubly linked list

Question

Hi, I currently have a simple database program that reads keys in from a text file and stores them in a doubly linked list (values are read later if they are required). Currently, I do a sequential search on the list, but that is clearly rather slow. I was hoping that there is another way to do. I was reading about binary trees (in particular, red black trees) but I don't know to much about them, and was hoping that I could gleam something from the stackoverflow hivemind :) I suppose my question is, what is the fastest way to do a search in a doubly linked list?

EDIT: Forgot to say that the list is sorted. Don't know if that changes anything. Also, the reason I only read in keys is that the max value length is 1024*32 bytes, which I feel is too large. Note that this is for an assignment, so "typical usage scenarios" don't apply. The professors are likely going to be stress testing the hell out of this thing, and I don't want to be mallocing blocks that big.

Answer 1

The fastest way to do a search in an unsorted doubly-linked list is one element at a time.

If you're trying to make search faster, don't use a linked list. Your idea of using a binary tree, for example, will certainly be faster, but as Matthew Flaschen said in comments, it's a completely different implementation from what you're using now.

Answer 2

There is a thing called a "skip list" that you could use.

It is a set of ordered lists. Each list skips more of the list items. This lets you do a form of binary search. However, maintaining the lists is more difficult.

Answer 3

Given that your doubly-linked list is sorted, and you have a list of items to search for, I suggest looking into the problem of building a self-balancing binary search tree. The tree construction could take some time, but it will be amortized if you have a long list of items to search for.