Re: filling area by color atack safety

From	Tim Rentsch <tr.17687@z991.linuxsc.com>
Newsgroups	comp.lang.c
Subject	Re: filling area by color atack safety
Date	2024-03-18 14:13 -0700
Organization	A noiseless patient Spider
Message-ID	<86cyrrnt00.fsf@linuxsc.com> (permalink)
References	(1 earlier) <ut4020$2s8ov$1@dont-email.me> <87wmq2jn7s.fsf@bsb.me.uk> <ut4b3c$2ugk7$1@dont-email.me> <86ttl3oo5b.fsf@linuxsc.com> <20240318142351.00001849@yahoo.com>

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Michael S <already5chosen@yahoo.com> writes:

> On Mon, 18 Mar 2024 03:00:32 -0700
> Tim Rentsch <tr.17687@z991.linuxsc.com> wrote:
>
>> bart <bc@freeuk.com> writes:
>>
>>> On 16/03/2024 13:55, Ben Bacarisse wrote:
>>>
>>>> Malcolm McLean <malcolm.arthur.mclean@gmail.com> writes:
>>>>
>>>>> Recursion make programs harder to reason about and prove correct.
>>>>
>>>> Are you prepared to offer any evidence to support this astonishing
>>>> statement or can we just assume it's another Malcolmism?
>>>
>>> You have evidence to suggest that the opposite is true?
>>
>> The claim is that recursion always makes programs harder to reason
>> about and prove correct.  It's easy to find examples that show
>> recursion does not always makes programs harder to reason about and
>> prove correct.
>>
>>> I personally find recursion hard work and errors much harder to
>>> debug.
>>
>> Most likely that's because you haven't had the relevant background
>> in learning how to program in a functional style.  That matches my
>> own experience:  it was only after learning how to write programs in
>> a functional style that I really started to appreciate the benefits
>> of using recursion, and to understand how to write and reason about
>> recursive programs.
>>
>>> It is also becomes much more important to show that will not cause
>>> stack overflow.
>>
>> In most cases it's enough to show that the stack depth never exceeds
>> log N for an input of size N.  I use recursion quite routinely
>> without there being any significant danger of stack overflow.  It's
>> a matter of learning which patterns are safe and which patterns are
>> potentially dangerous, and avoiding the dangerous patterns (unless
>> certain guarantees can be made to make them safe again).
>
> The problem in this case is that max. depth of recursion is O(N)
> where N is total number of pixels to change color.  So far I
> didn't find an obvious way to cut the worst case by more than
> small factor without turning recursive algorithm into something
> that is unrecognizably different from original and require proof
> of correction of its own.  Classic 'divide and conquer smaller
> part first" strategy does not appear applicable here, or at least
> not obviously.

Right.  I said as much in another reply to you.  This problem
is not well suited to a recursive solution.

To clarify my earlier comment, when I say I routinely use
recursion I do not mean I always use recursion.  Part of
understanding programming in a functional style is knowing
when not to use recursion as well as when to use it.

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filling area by color atack safety fir <fir@grunge.pl> - 2024-03-16 05:11 +0100
  Re: filling area by color atack safety Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-03-16 11:33 +0000
    Re: filling area by color atack safety Ben Bacarisse <ben.usenet@bsb.me.uk> - 2024-03-16 13:55 +0000
      Re: filling area by color atack safety bart <bc@freeuk.com> - 2024-03-16 14:41 +0000
        Re: filling area by color atack safety Ben Bacarisse <ben.usenet@bsb.me.uk> - 2024-03-17 10:42 +0000
        Re: filling area by color atack safety Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-18 03:00 -0700
          Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-18 14:23 +0200
            Re: filling area by color atack safety Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-18 14:13 -0700
            Re: filling area by color atack safety fir <fir@grunge.pl> - 2024-03-19 16:05 +0100
              Re: filling area by color atack safety bart <bc@freeuk.com> - 2024-03-19 17:16 +0000
                Re: filling area by color atack safety bart <bc@freeuk.com> - 2024-03-19 17:33 +0000
                Re: filling area by color atack safety fir <fir@grunge.pl> - 2024-03-19 23:07 +0100
                Re: filling area by color atack safety David Brown <david.brown@hesbynett.no> - 2024-03-20 09:29 +0100
        Re: filling area by color atack safety Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-18 03:04 -0700
      Re: filling area by color atack safety Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-03-16 14:45 +0000
        Re: filling area by color atack safety scott@slp53.sl.home (Scott Lurndal) - 2024-03-16 18:21 +0000
          Re: filling area by color atack safety Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-03-16 20:02 +0000
            Re: filling area by color atack safety "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-03-16 13:29 -0700
              Re: filling area by color atack safety "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-03-17 13:19 -0700
                Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-18 14:40 +0200
            Re: filling area by color atack safety fir <fir@grunge.pl> - 2024-03-19 23:23 +0100
          Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-17 15:32 +0200
        Re: filling area by color atack safety Ben Bacarisse <ben.usenet@bsb.me.uk> - 2024-03-17 11:25 +0000
          Re: filling area by color atack safety Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-03-17 12:37 +0000
            Re: filling area by color atack safety Kaz Kylheku <433-929-6894@kylheku.com> - 2024-03-17 17:11 +0000
            Re: filling area by color atack safety Ben Bacarisse <ben.usenet@bsb.me.uk> - 2024-03-23 00:21 +0000
            Re: filling area by color atack safety scott@slp53.sl.home (Scott Lurndal) - 2024-03-23 14:43 +0000
              Re: filling area by color atack safety Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-23 11:48 -0700
                Re: filling area by color atack safety scott@slp53.sl.home (Scott Lurndal) - 2024-03-24 20:48 +0000
                Re: filling area by color atack safety Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-28 22:51 -0700
    Re: filling area by color atack safety David Brown <david.brown@hesbynett.no> - 2024-03-16 15:40 +0100
      Re: filling area by color atack safety Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-03-16 15:09 +0000
        Re: filling area by color atack safety Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-03-17 14:56 +0000
          Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-17 17:42 +0200
          Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-17 18:25 +0200
            Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-17 19:39 +0200
              Re: filling area by color atack safety Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-18 11:36 -0700
                Re: filling area by color atack safety Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-03-18 18:51 +0000
                Re: filling area by color atack safety Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-18 23:10 -0700
                Re: filling area by color atack safety Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-03-19 12:06 +0000
            Re: filling area by color atack safety fir <fir@grunge.pl> - 2024-03-20 00:03 +0100
              Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-20 01:17 +0200
                Re: filling area by color atack safety fir <fir@grunge.pl> - 2024-03-20 00:30 +0100
                Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-20 12:06 +0200
                Re: filling area by color atack safety fir <fir@grunge.pl> - 2024-03-20 13:44 +0100
                Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-20 15:44 +0200
                Re: filling area by color atack safety fir <fir@grunge.pl> - 2024-03-20 15:17 +0100
          Re: filling area by color atack safety fir <fir@grunge.pl> - 2024-03-20 02:15 +0100
        Re: filling area by color atack safety David Brown <david.brown@hesbynett.no> - 2024-03-17 17:45 +0100
          Re: filling area by color atack safety Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-03-17 18:28 +0000
            Re: filling area by color atack safety David Brown <david.brown@hesbynett.no> - 2024-03-18 07:58 +0100
              Re: filling area by color atack safety Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-03-18 09:26 +0000
                Re: filling area by color atack safety David Brown <david.brown@hesbynett.no> - 2024-03-18 17:28 +0100
                Re: filling area by color atack safety Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-03-18 17:25 +0000
                Re: filling area by color atack safety scott@slp53.sl.home (Scott Lurndal) - 2024-03-18 17:42 +0000
                Re: filling area by color atack safety bart <bc@freeuk.com> - 2024-03-18 18:50 +0000
                Re: filling area by color atack safety David Brown <david.brown@hesbynett.no> - 2024-03-19 11:41 +0100
                Re: filling area by color atack safety Richard Harnden <richard.nospam@gmail.invalid> - 2024-03-19 12:19 +0000
                Re: filling area by color atack safety Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-03-18 11:10 -0700
                Keith-world (Was: filling area by color atack safety) gazelle@shell.xmission.com (Kenny McCormack) - 2024-03-18 22:42 +0000
                Re: filling area by color atack safety David Brown <david.brown@hesbynett.no> - 2024-03-19 12:31 +0100
                Re: filling area by color atack safety "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-03-18 16:18 -0700
                Re: filling area by color atack safety David Brown <david.brown@hesbynett.no> - 2024-03-19 11:32 +0100
      Re: filling area by color atack safety scott@slp53.sl.home (Scott Lurndal) - 2024-03-16 18:25 +0000
        Re: filling area by color atack safety Ben Bacarisse <ben.usenet@bsb.me.uk> - 2024-03-17 10:31 +0000
          Re: filling area by color atack safety Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-03-17 12:28 +0000
            Re: filling area by color atack safety bart <bc@freeuk.com> - 2024-03-17 12:49 +0000
          Re: filling area by color atack safety David Brown <david.brown@hesbynett.no> - 2024-03-17 17:59 +0100
      Re: filling area by color atack safety fir <fir@grunge.pl> - 2024-03-19 23:52 +0100
        Re: filling area by color atack safety fir <fir@grunge.pl> - 2024-03-20 01:36 +0100
    Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-17 14:46 +0200
      Re: filling area by color atack safety bart <bc@freeuk.com> - 2024-03-17 12:54 +0000
        Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-17 15:15 +0200
          Re: filling area by color atack safety bart <bc@freeuk.com> - 2024-03-17 13:23 +0000
            Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-17 15:37 +0200
              Re: filling area by color atack safety David Brown <david.brown@hesbynett.no> - 2024-03-17 18:05 +0100
            Re: filling area by color atack safety Ben Bacarisse <ben.usenet@bsb.me.uk> - 2024-03-17 14:10 +0000
              Re: filling area by color atack safety Spiros Bousbouras <spibou@gmail.com> - 2024-03-17 16:58 +0000
                Re: filling area by color atack safety Ben Bacarisse <ben.usenet@bsb.me.uk> - 2024-03-17 22:14 +0000
                Re: filling area by color atack safety bart <bc@freeuk.com> - 2024-03-17 22:21 +0000
      Re: filling area by color atack safety Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-18 02:30 -0700
        Re: filling area by color atack safety Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-03-18 11:08 +0000
          Re: filling area by color atack safety Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-18 22:54 -0700
            Re: filling area by color atack safety Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-03-19 11:41 +0000
              Re: filling area by color atack safety Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-19 21:19 -0700
      Re: filling area by color atack safety fir <fir@grunge.pl> - 2024-03-20 01:13 +0100
        Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-20 10:41 +0200
          Re: filling area by color atack safety fir <fir@grunge.pl> - 2024-03-20 15:20 +0100
    Re: filling area by color atack safety Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2024-03-17 14:27 +0000
      Re: filling area by color atack safety bart <bc@freeuk.com> - 2024-03-17 15:13 +0000
      Re: filling area by color atack safety Peter 'Shaggy' Haywood <phaywood@alphalink.com.au> - 2024-03-19 10:57 +1100
        Re: filling area by color atack safety fir <fir@grunge.pl> - 2024-03-20 01:26 +0100
  Re: filling area by color atack safety bart <bc@freeuk.com> - 2024-03-16 19:13 +0000
    Re: filling area by color atack safety bart <bc@freeuk.com> - 2024-03-16 20:23 +0000
      Re: filling area by color atack safety Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-03-16 20:29 +0000
    Re: filling area by color atack safety fir <fir@grunge.pl> - 2024-03-20 01:48 +0100
      Re: filling area by color atack safety Peter 'Shaggy' Haywood <phaywood@alphalink.com.au> - 2024-03-22 13:04 +1100
        Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-22 17:55 +0300
          Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-22 18:31 +0300
        Re: filling area by color atack safety fir <fir@grunge.pl> - 2024-03-23 11:06 +0100
  Re: filling area by color atack safety Peter 'Shaggy' Haywood <phaywood@alphalink.com.au> - 2024-03-17 18:03 +1100
  Re: filling area by color atack safety Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-18 13:09 -0700
    Re: filling area by color atack safety Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-18 22:42 -0700
      Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-19 13:18 +0200
        Re: filling area by color atack safety Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-03-19 11:57 +0000
          Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-19 15:49 +0200
            Re: filling area by color atack safety Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-19 21:43 -0700
              Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-20 10:56 +0200
                Re: filling area by color atack safety Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-20 06:51 -0700
          Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-19 19:18 +0200
            Re: filling area by color atack safety fir <fir@grunge.pl> - 2024-03-20 09:27 +0100
              Re: filling area by color atack safety fir <fir@grunge.pl> - 2024-03-20 09:39 +0100
              Re: filling area by color atack safety fir <fir@grunge.pl> - 2024-03-20 09:51 +0100
            Re: filling area by color atack safety Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-20 07:27 -0700
              Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-24 20:27 +0300
                Re: filling area by color atack safety Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-24 13:26 -0700
                Re: filling area by color atack safety "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-03-24 14:26 -0700
                Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-25 01:28 +0300
                Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-26 17:52 +0200
                Re: filling area by color atack safety Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-30 00:54 -0700
                Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-30 21:26 +0300
                Re: filling area by color atack safety Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-04-09 01:00 -0700
                Re: filling area by color atack safety Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-28 23:04 -0700
                Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-29 15:21 +0200
                Re: filling area by color atack safety Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-29 23:58 -0700
                Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-30 21:15 +0300
                Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-31 10:54 +0200
                Re: filling area by color atack safety Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-30 11:59 -0700
            Re: filling area by color atack safety Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-20 10:26 -0700
              Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-21 15:36 +0200
                Re: filling area by color atack safety Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-21 09:47 -0700
        Re: filling area by color atack safety Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-19 21:40 -0700
          Re: filling area by color atack safety "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-03-19 21:43 -0700
            Re: filling area by color atack safety "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-03-19 21:48 -0700
          Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-20 11:54 +0200
            Re: filling area by color atack safety Ben Bacarisse <ben.usenet@bsb.me.uk> - 2024-03-20 10:23 +0000
              Re: filling area by color atack safety Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-03-20 12:06 +0000
              Re: filling area by color atack safety Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-20 07:52 -0700
            Re: filling area by color atack safety Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-20 10:01 -0700
              Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-24 19:33 +0300
                Re: filling area by color atack safety Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-24 10:24 -0700
                Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-25 01:04 +0300
                Re: filling area by color atack safety - worst memory size Michael S <already5chosen@yahoo.com> - 2024-04-05 17:30 +0300

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