Ccc 2008

[whlue]

sparta @ Wed Feb 27, 2008 4:31 pm wrote:

i still can't understand why they had the same question for s5 and j5. Now i regret not even reading it over at the time cuz i thought s5 would be insanely hard >.>

My guess is that too many people got perfect in the junior last year (since it was a pretty easy problem set), so they wanted to spread out the range of the people who scored high.

[Sane]

Hi guys.

I'm a high school student from Ottawa. I signed up for this forum because it appears to discuss computer science competitions and algorithms-- two things I love to study. I'm looking forward to talking to many of you.

I finished the senior competition in 90 minutes. Question #4 was the hardest by far. The rest were good. But I think 2008 might have been the easiest year so far, next to 2007 and maybe 1996. So I spent the last 90 minutes of the competition checking and rechecking and checking it again. And now I'm so bloody anxious to get it marked. Haha. I'll give the solutions for 2008 when we get the go ahead from the other schools.

The last question (S5/J5) was a duplicate of a previous stage 2 question. I'm not sure if I should disclose any more information, since that might be going too far.

Oh: And by the way, the reason they used #5 for both junior and senior is because the input restriction is specifically tailored for different algorithmic approaches. A range of 1 <= x <= 8 goes nicely with brute force, whereas 1 <= x <= 30, goes nicely with the mysterious solution that will not be named.

[Fusha]

Sane @ Wed Feb 27, 2008 7:13 pm wrote:

Hi guys.

I'm a high school student from Ottawa. I signed up for this forum because it appears to discuss computer science competitions and algorithms-- two things I love to study. I'm looking forward to talking to many of you.

I finished the senior competition in 90 minutes. Question #4 was the hardest by far. The rest were good. But I think 2008 might have been the easiest year so far, next to 2007 and maybe 1996. So I spent the last 90 minutes of the competition checking and rechecking and checking it again. And now I'm so bloody anxious to get it marked. Haha. I'll give the solutions for 2008 when we get the go ahead from the other schools.

The last question (S5/J5) was a duplicate of a previous stage 2 question. I'm not sure if I should disclose any more information, since that might be going too far.

Oh: And by the way, the reason they used #5 for both junior and senior is because the input restriction is specifically tailored for different algorithmic approaches. A range of 1 <= x <= 8 goes nicely with brute force, whereas 1 <= x <= 30, goes nicely with the mysterious solution that will not be named.

How would you define brute force? A script that lists all the possible combinations and tries them, or something? Sorry, I'm not used to all these programming terms, I just script whatever comes to mind, and usually works

[stde]

Hi Sane Im just wondering how long did it take u to do s4?

and ya once all the schools are done. it would be so nice for you to post the solutions

[Sane]

It's not always the case, but in simplest terms, brute force is branching to every possibility. An analogy could be drawn to the recursive formula for the fibonacci sequence. Using the recursive formula for fib(100) will never finish, but other methods can be used to calculate it in polynomial time.

Brute force is probably the way that most people tried. But as soon as your numbers get up to 30, code that tries every combination will obviously not finish. However, for 8, it will suffice.

Edit: Number 4 took me the longest of all the questions. About 30 minutes.

[technograff]

Hi, guys, first post on the forum for me as well.

Anyhow, I just wrote the contest, and it made me realize how awful I am at programming . I got S1 done really fast, but I made it in a really inefficient fashion (ugh, don't even go there) so it didn't work for the higher test cases.

I did S2 without much trouble, but once the input cases got high my program crashed. I would LOVE to see a nice and efficient solution to this.

Past that, I got bit and pieces of code here and there, but nothing exciting.

I hope to absorb some programming prowess from here, so I hope replies get posted soon.

Out of curiosity: what languages did people use for this, and were they taught that language in school, or did they learn it as a hobby?

[OneOffDriveByPoster]

Since the problem set has been posted on the MMHS page...

[Sane]

I used C, as having learned it in school, and as a hobby.

By the way, I see you guys are familiar with the MMHS page. For sake of association, I'm "Aaron Voelker" from the list of credits, and also the mantainer of a similar site, http://codersblock.net/ccc/.

[A.J]

Senior was easier than I expected this year!
I got all 5, but I think my #4 is a bit flawed, but everything else should have been quite easy.

I wanted to know how other people did, so that I could make out the cuttoff for Stage 2.

Thx

[fantasy]

gah now i feel bad...i thought i did pretty good...but u guys made it seem so eazy

but if all the potential stage2ers did dwite...i should be ok i guess

[Fusha]

I wrote the contest in C. Everyone else in my school wrote it in java



I take it that we are allowed to post solutions to our problems now?

[DanielG]

I finished all 5, but my #4 had a flaw, rare but is probably in one of the test cases. and I made a stupid mistake on #3 by calling my array 0 .. 20, 0 .. 20 instead of 0 .. 21, 0 .. 21 (which is a must for my method of using an outer wall layer.
I think I got 1,2, and 5 perfect though.

[Cinjection]

I completed S1 and S2 easily and quickly and I think that they are pretty solid solutions. I essentially spent the rest of the time doing S3. I managed to get a working solution, but I know that it has a pretty large flaw in it so I know that I will not get the best mark on that particular problem. I think that S4 and S5 were out of my league anyway.

[Sane]

I just marked my solutions off the test files from MMHS.

74/75

I messed up something stupid too. Anyone beat me?

[CodeMonkey2000]

How are we suppose to do s4?