Re: how to parallel sort?

From:
peter koch <peter.koch.larsen@gmail.com>
Newsgroups:
comp.lang.c++
Date:
Sun, 9 Mar 2008 08:25:05 -0700 (PDT)
Message-ID:
<2a4f3ce9-4be1-4537-a603-bcdce4aa6a22@x41g2000hsb.googlegroups.com>
On 9 Mar., 02:39, nandor.sie...@gmail.com wrote:

I have a vector of integers something like v=(2,1,5,4). I'd like to
create a vector containing the indices in order of the values of this
vector. So the output would be (1,0,3,2). Note that
v[0]<v[1]<v[3]<v[2]. What's the easiest/most efficient way to do
this?

Is there something like a parallel sort that takes two vectors as its
input, sorts the first one and makes the same changes two the second
vector. So if v=(2,1,5,4) and w=(0,1,2,3) then parallel_sort(v,w)
would change this into v=(1,2,4,5) and w=(1,0,3,2).

Of course I can do this on my own with loops but I think that would
not be very efficient. I cannot match the built in STL sort algorithm.
What I'd like to know if there is an effective way of doing this with
the STL algorithms.


You can easily use STL. Just create the resulting vector with indices
from 0 to n and sort it using as sort criteria the values of the other
vectors index. Give it some time to learn it, then come back if you
get stuck.

/Peter

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