Ccc 2014

[linuxp]

How did everyone do? Expected cutoff for stage 2?

[xdxiaoming]

linuxp @ Wed Feb 26, 2014 9:59 am wrote:

How did everyone do? Expected cutoff for stage 2?

Expected cutoff: 60-65

[Panphobia]

Do you guys have the questions for the senior questions? If so I would be very thankful if someone posted 3,4,5, just wanna finish them for fun. Also I heard from a few people on the committee for the CCC that this year was a little harder than last, so I am guessing the cut off will be lower too.

[nullptr]

This year had some good questions, I liked S4 and S5 in particular. They took a different direction from the past 4 years, which all had graph theory problems. The online grader was really helpful. Anyone get perfect?

Quote:

Do you guys have the questions for the senior questions?

I can remember S4 and S5, but I think I should wait a little longer in case people in China are still writing or something.

[linuxp]

IMO cut off should be somewhere around 60

S4 was hard but solvable
S5 i have no idea how to do it perfectly

[Panphobia]

Yea I heard there was a geometry problem and a DP problem

[xdxiaoming]

S4: segment tree or sweep line algorithm
S5: find the 2D longest decreasing subsequence (DP+binary search)

[xdxiaoming]

Panphobia @ Wed Feb 26, 2014 10:39 am wrote:

Do you guys have the questions for the senior questions? If so I would be very thankful if someone posted 3,4,5, just wanna finish them for fun. Also I heard from a few people on the committee for the CCC that this year was a little harder than last, so I am guessing the cut off will be lower too.

Every registered student should have a copy of junior and a copy of senior tests. If you don't get them, you can ask your teacher for the printed tests.

[Panphobia]

I am in University, so I can't do that! But I love solving CCC problems, and I heard from a person from Waterloo that they are going to post the questions in like 3 weeks. I knew that people that registered got the problem packages, so I just asked for a scan .

[nullptr]

xdxiaoming @ Wed Feb 26, 2014 11:32 am wrote:

S5: find the 2D longest decreasing subsequence (DP+binary search)

Could you explain that a little more? I thought longest decreasing subsequence didn't permit repeats, but you can repeat points more than once in S5 -- or am I misunderstanding your solution?

My solution involved sorting the distances in increasing order and doing DP on those pairs. It got full marks but I'm interested to hear of other solutions. Did anyone get O(N^2)?

[Panphobia]

Is that Q5 similar to this question? http://projecteuler.net/problem=411 , this question is taking coordinates, sorting one dimension, then using longest non decreasing subsequence on the rest. Just wondering

[Nathan4102]

[mod edit]image removed[/]

Not quite scanner quality, but theres Q5 of the senior contest this year! I took a look at the senior contest before I started, and pretty much NOPED right out of it. Im good with iterations and arrays, but not the crazy searches/algorithms necessary for senior.

[Panphobia]

Do you have q4 and q3? I just finished q5

[Tony]

Certain schools administer the contest with a slight delay. Please wait to the end of the week before sharing exact questions / solutions.

[Nathan4102]

Ah ok, sorry about that. And pan I'll post them on the weekend I guess.