Any interest in a Project Euler Group? - Page 8 - Programming -- Two Plus Two Poker Forums

bachfan · 06-08-2011, 11:14 AM

Hope you all are having fun with this. Don't be afraid to skip around - some of the later problems are way, way harder than others.

- bachfan

I had the most fun/satisfaction solving this one:

http://projecteuler.net/index.php?se...roblems&id=215

MrWooster · 06-08-2011, 12:16 PM

Think its going to be a long time before I get that far.

**RoundTower** · 06-08-2011, 06:22 PM

Quote:

Originally Posted by bachfan

Hope you all are having fun with this. Don't be afraid to skip around - some of the later problems are way, way harder than others.

- bachfan

I had the most fun/satisfaction solving this one:

http://projecteuler.net/index.php?se...roblems&id=215

There's quite a few "doable" ones along these lines if you're interested, for some reason the dynamic programming ones seem to be aimed a little easier than the average problem. Or maybe I just see how to do them more easily.

If you read the solutions in the forum some people come up with amazingly short and/or fast solutions to even the hardest questions. I was proud of finding a neat solution to this one until I saw the forums and some people posting one-liners that run in 10ms!

I have 132 at the moment, I think I can probably solve another 20-30 and get to the next level on the site before I need to get better at maths or programming or both.

sorrow · 06-13-2011, 01:27 AM

I just solved problem 34 (http://projecteuler.net/index.php?se...problems&id=34 ) but i'm a bit stumped on how to find a reasonable upper bound on the calculations, and the first couple of pages of comments didn't seem to list a good upper limit either.

Any ideas?

gaming_mouse · 06-13-2011, 02:30 AM

Quote:

Originally Posted by sorrow

I just solved problem 34 (http://projecteuler.net/index.php?se...problems&id=34 ) but i'm a bit stumped on how to find a reasonable upper bound on the calculations, and the first couple of pages of comments didn't seem to list a good upper limit either.

Any ideas?

well eg,
8 * (9 !) = 2 903 040

yet any 8 digit number must be at least 10m. so you know at the very least you only have to test 7 digit numbers. you can do better than that i'm sure but it's simple.

jukofyork · 06-13-2011, 08:01 PM

You can build on the above and reduce the upper bound further:

7*9! = 2,540,160

which means the first digit cannot be higher than 2.

and all solutions where the first digit is 2 are invalid:

2! + 6*9! < 2,999,999

2! + 5*9! + 8! < 2,000,000

Therefore you can reduce the upper bound now to 1,999,999, as:

1! + 6*9! = 2,177,281 (which is >= 1,999,999)

Juk

jon_1van · 06-14-2011, 01:18 PM

Is this still a "live" effort. I'd be willing to jump in

gaming_mouse · 06-14-2011, 03:37 PM

Quote:

Originally Posted by RoundTower

There's quite a few "doable" ones along these lines if you're interested, for some reason the dynamic programming ones seem to be aimed a little easier than the average problem. Or maybe I just see how to do them more easily.

If you read the solutions in the forum some people come up with amazingly short and/or fast solutions to even the hardest questions. I was proud of finding a neat solution to this one until I saw the forums and some people posting one-liners that run in 10ms!

I have 132 at the moment, I think I can probably solve another 20-30 and get to the next level on the site before I need to get better at maths or programming or both.

what do u mean by "dyanamic programming" ones?

**goofyballer** · 06-14-2011, 05:17 PM

It's an algorithms term: http://en.wikipedia.org/wiki/Dynamic_programming

gaming_mouse · 06-14-2011, 05:44 PM

thx, def know the concept but never knew the name

Filip · 06-17-2011, 03:11 PM

Damn why did i find this sub forum, first i spent a hour thinking that with a handpicked team i could probably build a pretty good poker site for $1M and now a bunch of funny Euler problems.

Victor Kros · 06-22-2011, 08:04 AM

solved the first 50 and the last one (was 96th weeeeeeeee)

Filip · 06-22-2011, 03:09 PM

Quote:

Originally Posted by Victor Kros

solved the first 50 and the last one (was 96th weeeeeeeee)

328? Good job. Ive spent to much time on it.

mrcoughman · 06-25-2011, 06:39 PM

Can I get in on this Euler action?

ralu · 06-26-2011, 11:29 AM

Quote:

Originally Posted by bachfan

Hope you all are having fun with this. Don't be afraid to skip around - some of the later problems are way, way harder than others.

- bachfan

I had the most fun/satisfaction solving this one:

http://projecteuler.net/index.php?se...roblems&id=215

Nice problem, my solution in Python

Code:

def wall_counter(gn,r=0,c=0):
    if r==gn:
        yield c & (2**gn-1)
    elif r<gn:
        for j in [2,3]:
            for i in wall_counter(gn,r+j, c | (1<<(r+j))):
                yield i

gc=list(wall_counter(32))
lt = [[i2 for (i2,v2) in enumerate(gc) if  (v1|v2) == (v1^v2)] for (i1,v1) in enumerate(gc)]
sol=[[0 if j!= 0 else 1  for i in lt] for j in range(10)]

for i in range(1,10):
    for j in range(len(gc)):
        for k in lt[j]:
            sol[i][j] += sol[i-1][k]

print(sum(sol[9]))