Imprecise running time for topN?

[Magnus Lie Hetland]

I was reading the docs for std.algorithm, when I came across topN. This 
is, of course, a highly useful problem, with several solutions; I was a 
bit surprised to see the claim that it runs in linear time. As far as I 
know, the only ways of achieving that would be (1) using the 
super-elegant, but highly inefficient, algorithm of Blum, Floyd, Pratt, 
Rivest and Tarjan, often known as Select, or (2) using soft heaps. (The 
latter, I know less about.)

Checking the source, I found that -- as I suspected -- it uses the more 
common Randomized-Select (without actual randomization here, though), 
which only has an *expected* (or average-case) linear running time. It 
suffers the same worst-case problems as Quicksort.

I'm not objecting to the use of algorithm -- it's a good choice in 
practice -- but the docs should probably specify that the linear 
guarantee does not hold in the worst case?

-- 
Magnus Lie Hetland
http://hetland.org