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| From | Steve Thompson <stevet810@gmail.com> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: primitive instruction for programming |
| Date | 2015-04-17 02:25 +0000 |
| Organization | Friends of the Galactic Collective |
| Message-ID | <263NCi.tYn.6s7aE@gmail.com> (permalink) |
| References | (1 earlier) <mgg401$mdk$1@dont-email.me> <cdd18dd0-0c8b-4904-9590-daedd0bdaa39@googlegroups.com> <mgg66h$u4r$1@dont-email.me> <hLTsJW.t1p.ffTNE@gmail.com> <kfnr3rkys8d.fsf@x-alumni2.alumni.caltech.edu> |
On Thu, Apr 16, 2015 at 09:04:34AM -0700, Tim Rentsch wrote:
> Steve Thompson <stevet810@gmail.com> writes:
>
> > On Mon, Apr 13, 2015 at 11:36:56AM +0100, Bartc wrote:
> >> On 13/04/2015 11:28, asetofsymbols@gmail.com wrote:
> >>> Bartc wrote:
> >>> [code example that uses labels and goto's]
> >>
> >> This style of code is more error-prone. It's not even obvious
> >> where l1 needs to go; I can put it in several places and it would
> >> still compile, but the program won't work.
> >>
> >> This is something that just isn't a problem when using conventional
> >> control structures; why do you want to introduce a new source of
> >> bugs?
> >
> > One of the things I've been trying to do is an inorder traversal
> > of a binary tree without using recursion. With normal control
> > structures it doesn't seem possible without using goto.
>
> This is an interesting problem. It has a solution that is
> fairly simple but not immediately obvious. The key idea is
> to keep track of two different kinds of state - a (pointer to
> a) tree which represents a completely unprocessed subtree,
> and a stack of (pointers to) trees which represent subtrees
> that have had their left sides taken care of but still need
> their value processed and their right side done; loop over
> processing those as long as the unprocessed subtree is
> non-empty or the stack is non-empty, always processing an
> unprocessed subtree first. Here is a function to illustrate
> that does inorder printing (the Index type is just an
> ordinary integer type; note that the type Tree is a pointer
> type, so the 'stack' variable is a pointer to an array of
> pointers):
That is a succint description. As I wrote in a followup I should have
clarified that I found an algorithm, but it is rather goto oriented.
> void
> inorder_print( Tree root ){
> Tree *stack = malloc( 100 * sizeof *stack );
A balanced binary tree with a depth of 90 will easily exceed the
number of nodes one might hope to address with a 64-bit address space.
If the tree is unbalanced you should guard against stack overflow or
make sure that your insert/delete functions catch this.
> Index next = 0;
> Tree tree = root;
>
> while( tree || next > 0 ){
> if( tree ){
> stack[ next++ ] = tree;
> tree = tree->left;
> } else {
> tree = stack[ --next ];
> printf( " %d", tree->value );
> tree = tree->right;
> }
> }
> printf( "\n" );
>
> free( stack );
> }
I think one of the lessons here is that parent pointers are pretty
much superfluous to binary tree algorithms, and that recursion is
mostly avoidable.
Regards,
Steve Thompson
--
"If I had a nickel for every time some idiot called me about a
computer problem that turned out to be user error, I would be able to
retire and spend the rest of my days cultivating clues in my backyard
hillside garden." -- MysteryDog in 24hoursupport.helpdesk.
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primitive instruction for programming asetofsymbols@gmail.com - 2015-04-13 00:56 -0700
Re: primitive instruction for programming Richard Heathfield <rjh@cpax.org.uk> - 2015-04-13 09:24 +0100
Re: primitive instruction for programming asetofsymbols@gmail.com - 2015-04-13 01:59 -0700
Re: primitive instruction for programming Richard Heathfield <rjh@cpax.org.uk> - 2015-04-13 10:32 +0100
Re: primitive instruction for programming asetofsymbols@gmail.com - 2015-04-13 02:53 -0700
Re: primitive instruction for programming Bartc <bc@freeuk.com> - 2015-04-13 11:04 +0100
Re: primitive instruction for programming David Brown <david.brown@hesbynett.no> - 2015-04-13 14:10 +0200
Re: primitive instruction for programming Emiliano Gomes Padilha <egpadilha@gmail.com> - 2015-04-20 14:27 -0700
Re: primitive instruction for programming Emiliano Gomes Padilha <egpadilha@gmail.com> - 2015-04-20 15:12 -0700
Re: primitive instruction for programming Bartc <bc@freeuk.com> - 2015-04-21 00:17 +0100
Re: primitive instruction for programming Emiliano Gomes Padilha <egpadilha@gmail.com> - 2015-04-22 11:07 -0700
Re: primitive instruction for programming David Brown <david.brown@hesbynett.no> - 2015-04-21 09:04 +0200
Re: primitive instruction for programming Robert Wessel <robertwessel2@yahoo.com> - 2015-04-21 03:02 -0500
Re: primitive instruction for programming asetofsymbols@gmail.com - 2015-04-21 01:34 -0700
Re: primitive instruction for programming David Brown <david.brown@hesbynett.no> - 2015-04-21 11:34 +0200
Re: primitive instruction for programming Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-04-21 11:48 +0100
Re: primitive instruction for programming David Brown <david.brown@hesbynett.no> - 2015-04-21 13:10 +0200
Re: primitive instruction for programming Bartc <bc@freeuk.com> - 2015-04-21 10:53 +0100
Re: primitive instruction for programming Bartc <bc@freeuk.com> - 2015-04-13 20:09 +0100
Re: primitive instruction for programming asetofsymbols@gmail.com - 2015-04-13 12:48 -0700
Re: primitive instruction for programming David Brown <david.brown@hesbynett.no> - 2015-04-14 09:40 +0200
Re: primitive instruction for programming Bartc <bc@freeuk.com> - 2015-04-14 11:24 +0100
Re: primitive instruction for programming Robert Wessel <robertwessel2@yahoo.com> - 2015-04-14 05:39 -0500
Re: primitive instruction for programming David Brown <david.brown@hesbynett.no> - 2015-04-14 13:29 +0200
Re: primitive instruction for programming Bartc <bc@freeuk.com> - 2015-04-13 10:59 +0100
Re: primitive instruction for programming asetofsymbols@gmail.com - 2015-04-13 03:28 -0700
Re: primitive instruction for programming asetofsymbols@gmail.com - 2015-04-13 03:33 -0700
Re: primitive instruction for programming asetofsymbols@gmail.com - 2015-04-13 03:59 -0700
Re: primitive instruction for programming asetofsymbols@gmail.com - 2015-04-13 04:23 -0700
Re: primitive instruction for programming Bartc <bc@freeuk.com> - 2015-04-13 11:36 +0100
Re: primitive instruction for programming asetofsymbols@gmail.com - 2015-04-13 04:26 -0700
Re: primitive instruction for programming Bartc <bc@freeuk.com> - 2015-04-13 12:41 +0100
Re: primitive instruction for programming asetofsymbols@gmail.com - 2015-04-13 06:26 -0700
Re: primitive instruction for programming David Brown <david.brown@hesbynett.no> - 2015-04-13 15:33 +0200
Re: primitive instruction for programming asetofsymbols@gmail.com - 2015-04-13 06:44 -0700
Re: primitive instruction for programming David Brown <david.brown@hesbynett.no> - 2015-04-13 16:30 +0200
Re: primitive instruction for programming Ian Collins <ian-news@hotmail.com> - 2015-04-14 07:52 +1200
Re: primitive instruction for programming David Brown <david.brown@hesbynett.no> - 2015-04-14 09:47 +0200
Re: primitive instruction for programming raltbos@xs4all.nl (Richard Bos) - 2015-04-14 08:10 +0000
Re: primitive instruction for programming David Brown <david.brown@hesbynett.no> - 2015-04-14 10:40 +0200
Re: primitive instruction for programming Steve Thompson <stevet810@gmail.com> - 2015-04-13 17:52 +0000
Re: primitive instruction for programming Robert Wessel <robertwessel2@yahoo.com> - 2015-04-13 18:20 -0500
Re: primitive instruction for programming Robert Wessel <robertwessel2@yahoo.com> - 2015-04-13 18:33 -0500
Re: primitive instruction for programming Steve Thompson <stevet810@gmail.com> - 2015-04-14 19:51 +0000
Re: primitive instruction for programming Tim Rentsch <txr@alumni.caltech.edu> - 2015-04-16 09:04 -0700
Re: primitive instruction for programming Steve Thompson <stevet810@gmail.com> - 2015-04-17 02:25 +0000
Re: primitive instruction for programming Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-04-17 08:34 -0700
Re: primitive instruction for programming Bartc <bc@freeuk.com> - 2015-04-17 17:49 +0100
Re: primitive instruction for programming Steve Thompson <stevet810@gmail.com> - 2015-04-17 19:06 +0000
Re: primitive instruction for programming Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-04-17 20:45 -0700
Re: primitive instruction for programming Steve Thompson <stevet810@gmail.com> - 2015-04-18 16:43 +0000
Re: primitive instruction for programming Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-04-18 09:56 -0700
Re: primitive instruction for programming Stephen Sprunk <stephen@sprunk.org> - 2015-04-17 17:52 -0500
Re: primitive instruction for programming Morris Dovey <mrdovey@iedu.com> - 2015-04-17 18:02 -0500
Re: primitive instruction for programming Stephen Sprunk <stephen@sprunk.org> - 2015-04-17 19:26 -0500
Re: primitive instruction for programming Morris Dovey <mrdovey@iedu.com> - 2015-04-17 20:04 -0500
Re: primitive instruction for programming Michael Angelo Ravera <maravera@prodigy.net> - 2015-04-19 14:59 -0700
Re: primitive instruction for programming Richard Heathfield <rjh@cpax.org.uk> - 2015-04-20 00:19 +0100
Re: primitive instruction for programming Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-04-20 02:06 +0100
Re: primitive instruction for programming Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-04-20 02:26 +0100
Re: primitive instruction for programming Richard Heathfield <rjh@cpax.org.uk> - 2015-04-20 02:18 +0100
Re: primitive instruction for programming Tim Rentsch <txr@alumni.caltech.edu> - 2015-04-18 18:59 -0700
Re: primitive instruction for programming Steve Thompson <stevet810@gmail.com> - 2015-04-19 16:28 +0000
Re: primitive instruction for programming Richard Damon <Richard@Damon-Family.org> - 2015-04-19 17:16 -0400
Re: primitive instruction for programming Tim Rentsch <txr@alumni.caltech.edu> - 2015-04-22 15:28 -0700
Re: primitive instruction for programming John Bode <jfbode1029@gmail.com> - 2015-04-23 07:20 -0700
Re: primitive instruction for programming fmassei@gmail.com - 2015-04-13 03:07 -0700
Re: primitive instruction for programming asetofsymbols@gmail.com - 2015-04-13 09:47 -0700
Re: primitive instruction for programming fmassei@gmail.com - 2015-04-13 11:09 -0700
Re: primitive instruction for programming Noob <root@127.0.0.1> - 2015-04-13 20:43 +0200
Re: primitive instruction for programming fmassei@gmail.com - 2015-04-13 12:09 -0700
Re: primitive instruction for programming Xcott Craver <xcottcraver@gmail.com> - 2015-04-14 07:11 -0700
Re: primitive instruction for programming fmassei@gmail.com - 2015-04-14 07:28 -0700
Re: primitive instruction for programming Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-04-14 15:57 +0100
Re: primitive instruction for programming fmassei@gmail.com - 2015-04-14 08:13 -0700
Re: primitive instruction for programming fir <profesor.fir@gmail.com> - 2015-04-13 14:02 -0700
Re: primitive instruction for programming asetofsymbols@gmail.com - 2015-04-13 14:28 -0700
Re: primitive instruction for programming Bartc <bc@freeuk.com> - 2015-04-13 22:51 +0100
Re: primitive instruction for programming fmassei@gmail.com - 2015-04-13 14:58 -0700
Re: primitive instruction for programming Bartc <bc@freeuk.com> - 2015-04-13 23:25 +0100
Re: primitive instruction for programming fmassei@gmail.com - 2015-04-13 15:37 -0700
Re: primitive instruction for programming James Kuyper <jameskuyper@verizon.net> - 2015-04-13 19:09 -0400
Re: primitive instruction for programming fmassei@gmail.com - 2015-04-13 16:20 -0700
Re: primitive instruction for programming Robert Wessel <robertwessel2@yahoo.com> - 2015-04-13 18:03 -0500
Re: primitive instruction for programming asetofsymbols@gmail.com - 2015-04-13 20:58 -0700
Re: primitive instruction for programming fir <profesor.fir@gmail.com> - 2015-04-13 15:02 -0700
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