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From: "isaac2004" <isaac_2004@yahoo.com>
Newsgroups: comp.lang.ada
Subject: Re: Topological Sort Help
Date: 8 Feb 2007 10:53:37 -0800
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Date: 2007-02-08T10:53:37-08:00
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an exit when makes no sense in this situation because there is no
finite stopping condition, if you look at the algorithm provided, i
see it harder top implement an exit when loop

WHILE IsEmpty(G) /= False DO
      --                      S  := set of all vertices in V who have
no sucessors
      --                      if S is empty
      --                        hascycle := true;
      --                        return hascycle
      --                        end if
      --                       take the greatest element e in S
      --                      push e onto a stack
      --             remove all edge in E that have e as a
destination
      --            remove e from v
      --            end loop


if i am wrong please show me an algorithm that would work, thanks


On Feb 8, 10:38 am, "Jeffrey R. Carter" <jrcar...@acm.org> wrote:
> isaac2004 wrote:
> > the topological sort that i am trying to accomplish from this
> > structure will follow the algorithm that i have created from
> > others(its pretty much the same) the problem is im having trouble
> > setting up the while loop to traverse the array of digraph information
>
> An easy way to avoid confusing while loops is not to use them. Instead of
>
> Name : while Unintuitive_Negative_Logic_For_Loop_Continuation loop
>
> use
>
> Name : loop
>     exit Name when Intuitive_Positive_Logic_For_Loop_Exit;
>
> While loops, with their continuation condition, are generally better if
> you're doing correctness proofs, but if you're not, using exit
> conditions is usually clearer and more intuitive.
>
> --
> Jeff Carter
> "What I wouldn't give for a large sock with horse manure in it."
> Annie Hall
> 42