Re: [eclipse-clp-users] 7.11 puzzle

From: Joachim Schimpf <jschimpf_at_...311...>
Date: Tue, 13 Sep 2011 02:00:28 +0200
Sergey Dymchenko wrote:
> Hi!
> 
> I'm trying to solve this puzzle: http://programmingpraxis.com/2009/11/27/7-11/
> 
> Here is my very straightforward code:
> 
> :- lib(ic).
> solve :-
>     Sum = 711,
>     Product = 711,
>     Prices = [A, B, C, D],
>     A #> 0, B #> 0, C #> 0, D #> 0,
>     A + B + C + D #= Sum,
>     A * B * C * D #= Product * 1000000,
>     labeling(Prices),
>     writeln(Prices).
> 
> It works, but it's too slow.
> Is there any way to speed it up without being too clever and
> explicitly say to ECLiPSe that the prices of the four items must come
> from the list of divisors of 711?

It is much faster (1.8 instead of 63 seconds on my machine) if you use
domain splitting during search, i.e. replace labeling(Prices) with

    search(Prices, 0, input_order, indomain_split, complete, [])

This is probably always a good idea with relatively large domains
and convex constraints.

Other improvements?


Cheers,
Joachim
Received on Tue Sep 13 2011 - 00:00:34 CEST

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