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kotlinlang

Hello, I have a list with a few thousand entries in it. I need to add an element to the start of the list ... whats the best way to do this? Currently I'm doing this:

```val list = listOf(2,3,4)
val el = 1
val next = listOf(el) + list```
Thoughts?

If you intend to do this a lot, you should probably switch to a different datatype to avoid a big number of copies. ArrayDeque is suitable here: <https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.collections/-array-deque/>

ahh yes thats much closer to what im looking for:pray:

really what I want is a LIFO structure... is there something equivalent in the stdlib?

There is ArrayDeque, will it work for you?

I believe so, going to give it a try today

image.png

So I did a very brief comparison between list and deque ... it appears that deque is much slower?

Your meaurements are off. With a short test I get the following numbers:
```Elements	     List	   Deque
     100	    13082	    3590
    1000	     8736	    8034
   10000	    48796	   36239
  100000	   360435	  259785
 1000000	  6179680	 3074326
10000000	200453048	49068629```
As you can see, `Deque` is a lot more efficient after a certain threshold.