Re: [Boost-users] [BGL] Question about push_relabel_max_flow

From: Matthias Linkenheil (m.linkenheil_at_[hidden])
Date: 2005-03-10 12:09:09

Hi,

okay, "ai" is not checked against the end iterator because the assert 
function is called.
I don't know how to fix this problem so that the max flow result is right.

Suggestions are welcome?

Thanks,
Matthias Linkenheil

Doug Gregor schrieb:

>
> On Feb 25, 2005, at 4:50 AM, Matthias Linkenheil wrote:
>
>> Hello,
>>
>> I used the edmunds_karp_max_flow algorithm in my project and it 
>> worked fine.
>> Then I changed it to the push_relabel_max_flow algorithm but it 
>> doesn't work.
>> I get an access violation at line 562 in the push_relabel_max_flow.hpp .
>>
>> Have anyone an idea where the problem could be?
>>
>> Line 558 - line 565 of push_relabel_max_flow.hpp :     // do the bottom
>>    u = bos;
>>    ai = out_edges(u, g).first;
>>    while (excess_flow[u] > 0) {
>>        if (capacity[*ai] == 0 && is_residual_edge(*ai))
>>            push_flow(*ai);
>>        ++ai;
>>    }
>
>
> That's an odd bit of code... "ai" is never checked against the end 
> iterator (out_edges(u, g).second). Could you put in "assert(ai != 
> out_edges(u, g).second);"  as the first line of the while loop, to see 
> if that's what's happening?
>
>     Doug
>
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