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Groups > comp.lang.c > #157883

Re: Recursion v Memoization

From Ike Naar <ike@sdf.org>
Newsgroups comp.lang.c
Subject Re: Recursion v Memoization
Date 2020-12-30 05:47 +0000
Organization A noiseless patient Spider
Message-ID <slrn3kvoruo547.3p9.ike@sdf.org> (permalink)
References <rsg72i$eq4$1@gioia.aioe.org> <1WNGH.211578$9J69.27265@fx21.ams4>

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On 2020-12-29, Bart <bc@freeuk.com> wrote:
> This example shows how it might work for Fibonacci numbers up to 100, 
> even using inefficient recursion:
>
>   int fibonacci(int input)
>   {   enum {memlen=100};
>       static int memdata[memlen];
>
>       if (input<memlen && memdata[input])
>           return memdata[input];
>
>       if (input == 0 || input == 1)
>        {
>            memdata[input] = input;
>            return input;
>        }
>        else
>        {

Here's a bug: at this point, input can be >= memlen; if so, the
assignment to memdata[input] will write outside the array boundary.

>            memdata[input] = fibonacci(input - 1) + fibonacci(input - 2);
>            return memdata[input];
>        }
>   }

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Thread

Recursion v Memoization Real Troll <real.Troll@trolls.com> - 2020-12-29 16:30 -0500
  Re: Recursion v Memoization Bart <bc@freeuk.com> - 2020-12-29 22:17 +0000
    Re: Recursion v Memoization Ike Naar <ike@sdf.org> - 2020-12-30 05:47 +0000
      Re: Recursion v Memoization Bart <bc@freeuk.com> - 2020-12-30 11:55 +0000
  Re: Recursion v Memoization "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2020-12-29 21:51 -0800
  Re: Recursion v Memoization Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-12-31 00:46 -0800
    Re: Recursion v Memoization David Brown <david.brown@hesbynett.no> - 2020-12-31 16:12 +0100
      [OT] was: Recursion v Memoization Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-01-01 15:59 +0000
        Re: [OT] was: Recursion v Memoization David Brown <david.brown@hesbynett.no> - 2021-01-01 17:35 +0100
        Re: [OT] was: Recursion v Memoization Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-01-01 08:40 -0800
        Re: [OT] was: Recursion v Memoization Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2021-01-02 10:36 -0800
          Re: [OT] was: Recursion v Memoization "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2021-01-02 16:59 -0800
          Re: [OT] was: Recursion v Memoization "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2021-01-02 17:00 -0800
    Re: Recursion v Memoization Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2021-01-02 18:56 -0700
      Re: Recursion v Memoization Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-01-04 19:56 -0800
        Re: Recursion v Memoization beej@beej.us (Beej) - 2021-01-05 04:27 +0000
          Re: Recursion v Memoization Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-01-07 04:54 -0800
            Re: Recursion v Memoization beej@beej.us (Beej) - 2021-01-11 05:43 +0000
              Re: Recursion v Memoization Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-01-11 06:34 -0800
        Re: Recursion v Memoization Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2021-01-05 14:35 -0700
          Re: Recursion v Memoization Real Troll <real.troll@trolls.com> - 2021-01-05 16:45 -0500
            Re: Recursion v Memoization Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2021-01-05 15:33 -0700
          Re: Recursion v Memoization Jorgen Grahn <grahn+nntp@snipabacken.se> - 2021-01-06 09:40 +0000
            Re: Recursion v Memoization Jorgen Grahn <grahn+nntp@snipabacken.se> - 2021-01-06 17:09 +0000
          Re: Recursion v Memoization Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-01-07 06:37 -0800
  Re: Recursion v Memoization Andrey Tarasevich <andreytarasevich@hotmail.com> - 2020-12-31 02:33 -0800

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