Re: Re: Arithmetic Puzzle (so simple it's hard)
- To: mathgroup at smc.vnet.net
- Subject: [mg71679] Re: [mg71627] Re: Arithmetic Puzzle (so simple it's hard)
- From: Andrzej Kozlowski <akoz at mimuw.edu.pl>
- Date: Sun, 26 Nov 2006 03:49:12 -0500 (EST)
- References: <200611141006.FAA06684@smc.vnet.net><ejtda3$isg$1@smc.vnet.net> <200611251037.FAA15617@smc.vnet.net>
Yes indeed, but this is still "brute force", and that is what Janos
wrote he lacks rather than functional programming skills. He tried to
use intelligence (in this case a genetic algorithm) as did Daniel
Lichtblau. The trouble is that this is the sort of problem where
brute force always wins and intelligence comes off badly beaten up.
It's like fighting a battle on a complete plain field, with no hills,
rivers, or anything else that you can use to make up for the enemy's
superior numbers; even Hannibal, Caesar or Napoleon would be
helpless. In that sense it is indeed "so simple that it's hard".
Andrzej Kozlowski
On 25 Nov 2006, at 19:37, croddie at princeton.edu wrote:
> Janos: get used to functional programming!
>
> Simple program, not too slow; plus you can read and understand it:
>
> doesitwork[partition_] :=
> Module[{b, u, t, a, s, k, f, e},
> {b, u, t, a, s, k, f, e} = partition;
> (100b + 10u +t)(100a + 10s + k) == 10000f + 1000e +
> 100a + 10s + t];
> Timing[Select [Permutations[{0, 1, 2, 4, 5, 6, 7, 9}], doesitwork]]
>
> Output:
> {1.578 Second, {{0, 5, 6, 4, 9, 1, 2, 7}, {6, 7, 0, 1, 4, 2, 9, 5}}}
>
>
> János wrote:
>
>> Any suggestions to make it faster would be highly appreciated. /It
>> took 526 seconds to run with above parameters/
>>
>> János
>> On Nov 14, 2006, at 5:06 AM, Bruce Colletti wrote:
>>
>>> How would this problem be solved in Mathematica?
>
- References:
- Arithmetic Puzzle (so simple it's hard)
- From: Bruce Colletti <vze269bv@verizon.net>
- Re: Arithmetic Puzzle (so simple it's hard)
- From: croddie@princeton.edu
- Arithmetic Puzzle (so simple it's hard)