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From: David House <dhouse@janestreet.com>
To: Malcolm Matalka <mmatalka@gmail.com>
Cc: 沈胜宇 <syshen@nudt.edu.cn>, caml-list <caml-list@inria.fr>
Subject: Re: [Caml-list] [OCAML]:: the cost of List.length
Date: Mon, 15 Apr 2013 07:29:21 +0100	[thread overview]
Message-ID: <CAK=fH+iayL1PmbZnu4MS4t68cgm0G-7k0i4QVR410N1dtBYNqg@mail.gmail.com> (raw)
In-Reply-To: <CAKziXDVh8MMddwK85NG9piX4tdiXQnqTA7_32jNPLyn_pyuxOw@mail.gmail.com>

Lists are naive linked lists, i.e. either the empty list or a pair of
an element and a list. Finding the length means walking to the end of
the list.

There is probably a better data structure than lists for your
purposes. What operations do you need, and which ones need to be fast?

On 14 April 2013 14:32, Malcolm Matalka <mmatalka@gmail.com> wrote:
> O(n)
>
> Den 14 apr 2013 15:27 skrev "沈胜宇" <syshen@nudt.edu.cn>:
>
>> Dear all:
>>
>> I have a program that run very fast.
>>
>> Recently, I add a call to List.length to this old program's inner loop,
>> which make it significantly slower.
>>
>> So what is the cost of List.length, is it liner to the size of the list?
>> or is a const?
>>
>> Shen

  reply	other threads:[~2013-04-15  6:29 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-04-14 13:23 沈胜宇
2013-04-14 13:32 ` Malcolm Matalka
2013-04-15  6:29   ` David House [this message]
2013-04-15 11:05     ` 沈胜宇

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