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Groups > comp.lang.c > #147309
| Subject | Re: Challenge for Feeb: dealing with large numbers in C |
|---|---|
| Newsgroups | comp.lang.c |
| References | (14 earlier) <87lft6rqy6.fsf@bsb.me.uk> <5a9c3f4b-1204-4d40-8d5b-438b4cfe3bf3@googlegroups.com> <87a79lsmm7.fsf@bsb.me.uk> <lKrtF.1173925$Nw3.180880@fx40.am4> <44a985ee-1d94-4af9-8a38-124c57cc0a4f@googlegroups.com> |
| From | Bart <bc@freeuk.com> |
| Message-ID | <BhHtF.1932$Fr3.640@fx39.am4> (permalink) |
| Organization | virginmedia.com |
| Date | 2019-10-28 19:26 +0000 |
On 28/10/2019 18:05, already5chosen@yahoo.com wrote:
> On Monday, October 28, 2019 at 3:44:59 AM UTC+2, Bart wrote:
>> This has a somewhat different inner loop than yours. It turns out to be
>> about 4 times as fast as my bubble sort for the same random data, in the
>> same language and for larger data sets.
>>
>> However, if I was sorting data for which that timing was important, I'd
>> use a quick-sort routine. Or some other approach entirely if I knew the
>> data lent itself to that.
>>
>
>
> Count-based sorting algorithms sort arrays of millions of random 32-bit or 64-bit integers many times faster than quicksort.
That sounds like what I meant by 'some other approach entirely if I knew
the data lent itself to that'. (And like the histogram method posted in
the thread.)
>It does not make quicksort useless.
Quicksort, insertion sort etc are general purpose algorithms that will
work with any values of data. (Although they can also be used with a
user-supplied compare function to sort a table of indices, when the
sorting has to be across parallel sets of data.)
> The same apply to quicksort vs straight insertion sort.
> Sometimes (big records, quick comparisons) the same applies to straight insertion sort vs direct selection sort.
> The same *never* apply to straight insertion sort vs bubblesort.
>
> Ben is simply correct in everything he said. And you are simply stubborn for no reason.
I just have a soft soft for bubble sort; the way it works, the way the
action is always localised, is aesthetically pleasing.
It just has a slightly lower threshold at which it stops being viable
than insertion sort, and a much lower threshold than quicksort.
In the same way that interpreted languages have a certain threshold at
which the task to be accomplished will be more practical in compiled
code. Or the magnitudes of bignum where a simple library will become too
slow compared with a sophisticated one.
In my own code, general purpose sort is used rarely as I would use other
techniques like the ones alluded to above.
BTW, I posted a quicksort routine earlier that sorted 10 million random
numbers in about 1 second. I can use a counting technique to reduce to
50msec (20 times faster), since I know the range of numbers is 0 to
RAND_MAX (0 to 32767 on my machine). However, I don't consider this a
general purpose sort:
-------------------------------------
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
enum {N=10000000};
typedef long long int T;
void ccsort(T *a, int n) {
int *counts = malloc((RAND_MAX+1)*sizeof(int));
int k,m;
memset(counts,0,(RAND_MAX+1)*sizeof(int));
for (int i=0; i<n; ++i) {
++counts[a[i]];
}
k=0;
for (int i=0; i<=RAND_MAX; ++i) {
m=counts[i];
while (m--) {
a[k++]=i;
}
}
}
int issorted(T *a,int n) {
for (int i=0; i<n-1; ++i) {
if (a[i]>a[i+1]) return 0;
}
return 1;
}
int main(void) {
T *a = malloc(N*sizeof(T));
int t;
for (int i=0; i<N; ++i) a[i]=rand();
t=clock();
ccsort(a,N);
t=clock()-t;
printf("Issorted(A) = %s N=%d\n",(issorted(a,N)?"Yes":"No"),N);
printf("Time = %d ticks\n",t);
}
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Challenge for Feeb: dealing with large numbers in C DFS <nospam@dfs.com> - 2019-10-20 18:12 -0400
Re: Challenge for Feeb: dealing with large numbers in C Barry Schwarz <schwarzb@delq.com> - 2019-10-20 18:33 -0700
Re: Challenge for Feeb: dealing with large numbers in C DFS <nospam@dfs.com> - 2019-10-20 23:16 -0400
Re: Challenge for Feeb: dealing with large numbers in C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-10-21 13:15 +0100
Re: Challenge for Feeb: dealing with large numbers in C DFS <nospam@dfs.com> - 2019-10-21 14:40 -0400
Re: Challenge for Feeb: dealing with large numbers in C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-10-22 00:54 +0100
Re: Challenge for Feeb: dealing with large numbers in C David Brown <david.brown@hesbynett.no> - 2019-10-22 10:05 +0200
Re: Challenge for Feeb: dealing with large numbers in C Tim Rentsch <tr.17687@z991.linuxsc.com> - 2019-10-23 07:18 -0700
Re: Challenge for Feeb: dealing with large numbers in C Manfred <noname@invalid.add> - 2019-10-26 20:01 +0200
Re: Challenge for Feeb: dealing with large numbers in C DFS <nospam@dfs.com> - 2019-10-26 17:50 -0400
Re: Challenge for Feeb: dealing with large numbers in C Manfred <noname@add.invalid> - 2019-10-28 16:33 +0100
Re: Challenge for Feeb: dealing with large numbers in C Barry Schwarz <schwarzb@delq.com> - 2019-10-21 07:56 -0700
Re: Challenge for Feeb: dealing with large numbers in C Bart <bc@freeuk.com> - 2019-10-21 16:46 +0100
Re: Challenge for Feeb: dealing with large numbers in C DFS <nospam@dfs.com> - 2019-10-21 14:57 -0400
Re: Challenge for Feeb: dealing with large numbers in C Bart <bc@freeuk.com> - 2019-10-21 20:53 +0100
Re: Challenge for Feeb: dealing with large numbers in C DFS <nospam@dfs.com> - 2019-10-21 16:05 -0400
Re: Challenge for Feeb: dealing with large numbers in C Bart <bc@freeuk.com> - 2019-10-21 21:12 +0100
Re: Challenge for Feeb: dealing with large numbers in C DFS <nospam@dfs.com> - 2019-10-21 20:08 -0400
Re: Challenge for Feeb: dealing with large numbers in C David Brown <david.brown@hesbynett.no> - 2019-10-22 10:27 +0200
Re: Challenge for Feeb: dealing with large numbers in C Bart <bc@freeuk.com> - 2019-10-22 19:45 +0100
Re: Challenge for Feeb: dealing with large numbers in C Eli the Bearded <*@eli.users.panix.com> - 2019-10-22 19:58 +0000
Re: Challenge for Feeb: dealing with large numbers in C DFS <nospam@dfs.com> - 2019-10-23 11:46 -0400
Re: Challenge for Feeb: dealing with large numbers in C Bart <bc@freeuk.com> - 2019-10-23 20:02 +0100
Re: Challenge for Feeb: dealing with large numbers in C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-10-24 01:38 +0100
Re: Challenge for Feeb: dealing with large numbers in C DFS <nospam@dfs.com> - 2019-10-23 22:10 -0400
Re: Challenge for Feeb: dealing with large numbers in C Ike Naar <ike@sdf.lonestar.org> - 2019-10-24 07:24 +0000
Re: Challenge for Feeb: dealing with large numbers in C DFS <nospam@dfs.com> - 2019-10-24 09:29 -0400
Re: Challenge for Feeb: dealing with large numbers in C James Kuyper <jameskuyper@alumni.caltech.edu> - 2019-10-24 08:45 -0700
Re: Challenge for Feeb: dealing with large numbers in C DFS <nospam@dfs.com> - 2019-10-24 11:56 -0400
Re: Challenge for Feeb: dealing with large numbers in C Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2019-10-24 09:13 -0700
Re: Challenge for Feeb: dealing with large numbers in C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-10-24 18:28 +0100
Re: Challenge for Feeb: dealing with large numbers in C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-10-24 10:36 +0100
Re: Challenge for Feeb: dealing with large numbers in C DFS <nospam@dfs.com> - 2019-10-24 09:26 -0400
Re: Challenge for Feeb: dealing with large numbers in C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-10-24 18:29 +0100
Re: Challenge for Feeb: dealing with large numbers in C DFS <nospam@dfs.com> - 2019-10-24 14:38 -0400
Re: Challenge for Feeb: dealing with large numbers in C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-10-24 21:30 +0100
Re: Challenge for Feeb: dealing with large numbers in C Bart <bc@freeuk.com> - 2019-10-24 11:30 +0100
Re: Challenge for Feeb: dealing with large numbers in C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-10-24 20:36 +0100
Re: Challenge for Feeb: dealing with large numbers in C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-10-24 21:34 +0100
Re: Challenge for Feeb: dealing with large numbers in C Bart <bc@freeuk.com> - 2019-10-24 22:42 +0100
Re: Challenge for Feeb: dealing with large numbers in C DFS <nospam@dfs.com> - 2019-10-24 18:59 -0400
Re: Challenge for Feeb: dealing with large numbers in C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-10-25 02:48 +0100
Re: Challenge for Feeb: dealing with large numbers in C Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2019-10-26 04:33 -0700
Re: Challenge for Feeb: dealing with large numbers in C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-10-26 17:21 +0100
Re: Challenge for Feeb: dealing with large numbers in C Bart <bc@freeuk.com> - 2019-10-26 18:47 +0100
Re: Challenge for Feeb: dealing with large numbers in C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-10-26 23:24 +0100
Re: Challenge for Feeb: dealing with large numbers in C Bart <bc@freeuk.com> - 2019-10-27 00:29 +0100
Re: Challenge for Feeb: dealing with large numbers in C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-10-27 01:58 +0100
Re: Challenge for Feeb: dealing with large numbers in C Bart <bc@freeuk.com> - 2019-10-27 12:02 +0000
Re: Challenge for Feeb: dealing with large numbers in C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-10-28 02:08 +0000
Re: Challenge for Feeb: dealing with large numbers in C Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2019-10-26 14:29 -0600
Re: Challenge for Feeb: dealing with large numbers in C Keith Thompson <kst-u@mib.org> - 2019-10-26 13:36 -0700
Re: Challenge for Feeb: dealing with large numbers in C Bart <bc@freeuk.com> - 2019-10-26 22:06 +0100
Re: Challenge for Feeb: dealing with large numbers in C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-10-26 23:04 +0100
Re: Challenge for Feeb: dealing with large numbers in C David Brown <david.brown@hesbynett.no> - 2019-10-27 12:49 +0100
Re: Challenge for Feeb: dealing with large numbers in C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-10-27 18:20 +0000
Re: Challenge for Feeb: dealing with large numbers in C David Brown <david.brown@hesbynett.no> - 2019-10-27 22:45 +0100
Re: Challenge for Feeb: dealing with large numbers in C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-10-28 00:08 +0000
Re: Challenge for Feeb: dealing with large numbers in C Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2019-10-27 14:57 -0700
Re: Challenge for Feeb: dealing with large numbers in C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-10-28 01:08 +0000
Re: Challenge for Feeb: dealing with large numbers in C Bart <bc@freeuk.com> - 2019-10-28 01:44 +0000
Re: Challenge for Feeb: dealing with large numbers in C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-10-28 02:31 +0000
Re: Challenge for Feeb: dealing with large numbers in C Bart <bc@freeuk.com> - 2019-10-28 10:42 +0000
Re: Challenge for Feeb: dealing with large numbers in C Bart <bc@freeuk.com> - 2019-10-28 12:45 +0000
Re: Challenge for Feeb: dealing with large numbers in C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-10-28 17:39 +0000
Re: Challenge for Feeb: dealing with large numbers in C David Brown <david.brown@hesbynett.no> - 2019-10-28 20:31 +0100
Re: Challenge for Feeb: dealing with large numbers in C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-10-28 20:22 +0000
Re: Challenge for Feeb: dealing with large numbers in C David Brown <david.brown@hesbynett.no> - 2019-10-28 22:07 +0100
Re: Challenge for Feeb: dealing with large numbers in C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-10-28 22:22 +0000
Re: Challenge for Feeb: dealing with large numbers in C David Brown <david.brown@hesbynett.no> - 2019-10-29 10:17 +0100
Re: Challenge for Feeb: dealing with large numbers in C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-10-29 11:21 +0000
Re: Challenge for Feeb: dealing with large numbers in C already5chosen@yahoo.com - 2019-10-28 11:05 -0700
Re: Challenge for Feeb: dealing with large numbers in C Bart <bc@freeuk.com> - 2019-10-28 19:26 +0000
Re: Challenge for Feeb: dealing with large numbers in C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-10-28 21:08 +0000
Re: Challenge for Feeb: dealing with large numbers in C Bart <bc@freeuk.com> - 2019-10-28 21:57 +0000
Re: Challenge for Feeb: dealing with large numbers in C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-10-28 23:59 +0000
Re: Challenge for Feeb: dealing with large numbers in C Bart <bc@freeuk.com> - 2019-10-29 00:53 +0000
Re: Challenge for Feeb: dealing with large numbers in C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-10-29 01:09 +0000
Re: Challenge for Feeb: dealing with large numbers in C Bart <bc@freeuk.com> - 2019-10-29 01:32 +0000
Re: Challenge for Feeb: dealing with large numbers in C DFS <nospam@dfs.com> - 2019-10-28 22:44 -0400
Re: Challenge for Feeb: dealing with large numbers in C Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2019-10-29 03:05 -0700
Re: Challenge for Feeb: dealing with large numbers in C Bart <bc@freeuk.com> - 2019-10-29 11:12 +0000
Re: Challenge for Feeb: dealing with large numbers in C already5chosen@yahoo.com - 2019-10-29 04:19 -0700
Re: Challenge for Feeb: dealing with large numbers in C Bart <bc@freeuk.com> - 2019-10-29 11:47 +0000
Re: Challenge for Feeb: dealing with large numbers in C Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2019-10-29 05:03 -0700
Re: Challenge for Feeb: dealing with large numbers in C Bart <bc@freeuk.com> - 2019-10-29 13:16 +0000
Re: Challenge for Feeb: dealing with large numbers in C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-10-29 17:13 +0000
Re: Challenge for Feeb: dealing with large numbers in C Bart <bc@freeuk.com> - 2019-10-29 17:35 +0000
Re: Challenge for Feeb: dealing with large numbers in C Ike Naar <ike@sdf.lonestar.org> - 2019-10-30 07:19 +0000
Re: Challenge for Feeb: dealing with large numbers in C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-10-29 16:19 +0000
Re: Challenge for Feeb: dealing with large numbers in C Bart <bc@freeuk.com> - 2019-10-29 16:50 +0000
Re: Challenge for Feeb: dealing with large numbers in C Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2019-10-29 10:03 -0700
Re: Challenge for Feeb: dealing with large numbers in C Bart <bc@freeuk.com> - 2019-10-29 17:13 +0000
Re: Challenge for Feeb: dealing with large numbers in C already5chosen@yahoo.com - 2019-10-29 10:23 -0700
Re: Challenge for Feeb: dealing with large numbers in C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-10-29 22:20 +0000
Re: Challenge for Feeb: dealing with large numbers in C already5chosen@yahoo.com - 2019-10-30 03:04 -0700
Re: Challenge for Feeb: dealing with large numbers in C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-10-30 15:39 +0000
Re: Challenge for Feeb: dealing with large numbers in C Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2019-10-30 09:02 -0700
Re: Challenge for Feeb: dealing with large numbers in C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-10-30 19:35 +0000
Re: Challenge for Feeb: dealing with large numbers in C already5chosen@yahoo.com - 2019-10-30 14:11 -0700
Re: Challenge for Feeb: dealing with large numbers in C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-10-31 03:34 +0000
Re: Challenge for Feeb: dealing with large numbers in C Tim Rentsch <tr.17687@z991.linuxsc.com> - 2019-11-04 17:02 -0800
Re: Challenge for Feeb: dealing with large numbers in C Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2019-10-26 12:30 -0400
Re: Challenge for Feeb: dealing with large numbers in C Robert Wessel <robertwessel2@yahoo.com> - 2019-10-26 12:03 -0500
Re: Challenge for Feeb: dealing with large numbers in C Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2019-10-26 14:25 -0600
Re: Challenge for Feeb: dealing with large numbers in C Tim Rentsch <tr.17687@z991.linuxsc.com> - 2019-10-24 18:06 -0700
Re: Challenge for Feeb: dealing with large numbers in C Bart <bc@freeuk.com> - 2019-10-21 22:44 +0100
Re: Challenge for Feeb: dealing with large numbers in C DFS <nospam@dfs.com> - 2019-10-21 19:00 -0400
Re: Challenge for Feeb: dealing with large numbers in C Johann 'Myrkraverk' Oskarsson <johann@myrkraverk.invalid> - 2019-10-21 10:20 +0800
Re: Challenge for Feeb: dealing with large numbers in C Bart <bc@freeuk.com> - 2019-10-21 12:44 +0100
Re: Challenge for Feeb: dealing with large numbers in C Johann 'Myrkraverk' Oskarsson <johann@myrkraverk.invalid> - 2019-10-21 10:24 +0800
Re: Challenge for Feeb: dealing with large numbers in C DFS <nospam@dfs.com> - 2019-10-20 23:05 -0400
Re: Challenge for Feeb: dealing with large numbers in C Johann 'Myrkraverk' Oskarsson <johann@myrkraverk.invalid> - 2019-10-21 11:32 +0800
Re: Challenge for Feeb: dealing with large numbers in C Autist <autist69@gmail.com> - 2019-10-29 15:15 +0100
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