garakchy's blog

Topcoder SRM 722
By garakchy, history, 7 years ago, In English

Edit 4: TC SRM 722 starts in a few minutes. Please register, ASAP. My best wishes to you all.

Hi CodeForcers, TopCoder sent me an email which states that Harvard — NASA Tournament Lab and TopCoder will be sponsoring this SRM (722) and have decided to pay $5 to recognize community members who engage in this SRM(722). The SRM 722 starts on 12 Oct 2017, Thursday at 7:00 am UTC-4.

The email is below:

Hi [username],

You have less than a week to prepare! Topcoder Single Round Match 722 is almost here! Topcoder SRM 722 is scheduled to start at 07:00 UTC -4 on Oct 12, 2017.

The Harvard-NASA Tournament Lab and Topcoder will be sponsoring this SRM and have decided to pay $5 to recognize community members who engage in this SRM.

You can pre-register and see the match details here.

Best of luck! The Topcoder Team

Information on the Harvard-NASA Tournament Lab SRM Run

Edit: I don't know how to add it to the Google Calendar in CF, please somebody do it. Good luck, everybody!

Edit 2: Edit 1 is still valid. Please, somebody add it to the Calendar.

Edit 3: I'm very sorry guys, I got confused about the time. Email indicates UTC -4, but the countdown on TC site is confusing. Hopefully, I set the time correct now. Please check TC site yourselves also and make sure you get the time right. Sorry again for inconvenience.

  • Vote: I like it
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  • Vote: I do not like it

Comments Comments (29)
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7 years ago, # |
← Rev. 2   Vote: I like it 0 Vote: I do not like it

My mail says I will get the "SRM ENGAGE Award" and "This award will be posted on your private Dashboard and sent to you as a sticker for your laptop after completing the SRM.", nothing about 5$.

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7 years ago, # |
  Vote: I like it -25 Vote: I do not like it

What are the requirements to win those 5$ ? Should we just register? Or are there some requirements like being a member for 6 months or having participated in at least one srm or something like that?

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7 years ago, # |
  Vote: I like it +10 Vote: I do not like it

After ~1h Fun SRM will start.

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7 years ago, # |
  Vote: I like it 0 Vote: I do not like it

The email says 7:00 UTC -4, but this announcement 7:00 UTC. Schedule of SRMs is nowhere to be found on Topcoder (it is not in the web arena). So, what's the truth?

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7 years ago, # |
  Vote: I like it 0 Vote: I do not like it

i got two emails 1st-5$ prize 2nd-sticker for laptop

dont know what exactly is gonna happen. i would like 5$ by the way, make a good dinner here;-)

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    7 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    Can u plz tell why did u recieve those two emails?I secured rank 1 in div 2 ranklist,is there some sticker for me too? :P :)

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7 years ago, # |
  Vote: I like it +10 Vote: I do not like it

Reminder: Contest starts in 3hr 30mins. Registeration is already started.

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7 years ago, # |
  Vote: I like it 0 Vote: I do not like it

If I open all three problem simultaneously, do point decay start for all problems? Can someone explain how the point decay happens in topcoder?

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7 years ago, # |
← Rev. 2   Vote: I like it +47 Vote: I do not like it

Today i expected to solve problems but i only wrote code...

Div 1 hard.

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    7 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    Is the run time for the approach N * 2M * 2M?

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      7 years ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      O(n × m × 2min(n, m)).

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        7 years ago, # ^ |
          Vote: I like it 0 Vote: I do not like it

        Could please elaborate on where we the optimization happens? I have elaborated my understanding below.

        below lines of code contribute to N * 2M

        	for (int x=0; x<n; ++x)
		for (int mask=0; mask<(1<<m); ++mask)

        Below lines of code contribute to another 2M

        			calc (x, y+1, mask, next_mask | my_mask);
			if (y+1 < m && ! (mask & my_mask) && ! (mask & (my_mask << 1)))
				calc (x, y+2, mask, next_mask);
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7 years ago, # |
  Vote: I like it +78 Vote: I do not like it

I didn't expect a problem such as 600 to turn up at TopCoder Div1 rated contest, ever. With the added irony of wrong constraints which show a lack of corner case testing. Is cgy4ever still TC Algo admin?

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    7 years ago, # ^ |
      Vote: I like it +22 Vote: I do not like it

    I talked with t-mac and cgy4ever (TopCoder admins), here's the reply:

    They knew that the problems were not great for d1 and it was originally planned as an unrated fun SRM. However, due to business reasons, it was important to have at least one rated SRM before TCO, and t-mac decided to use the problems in a rated SRM. There was some misunderstanding between t-mac and cgy4ever, however, so I asked t-mac to discuss with cgy4ever next time.

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      7 years ago, # ^ |
        Vote: I like it +8 Vote: I do not like it

      To be fair, I think the 350 would have made a very nice Div1 Easy.

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7 years ago, # |
  Vote: I like it +29 Vote: I do not like it

Probably the easiest Div2 contest in topcoder history.

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7 years ago, # |
← Rev. 7   Vote: I like it +20 Vote: I do not like it

I've solved (not saying that it will pass / UPD: IT FAILED / UPD2: IT PASSED AGAIN) Div1 Hard in a interesting way:
1. First I found an O(2W·H·FW) solution which FW is W-th Fibonacci number, but since H, W ≤ 14 I thought that it won't pass.
2. I found that it can overflow 64bit integers, so I asked to admins.
3. Admin said "Yes, it overflows — so I'll change H, W to 12".
4. I was happy — my O(2W·H·FW) solution will pass with enough speed.

But, many people are discussing about problem quality of this contest, so I started a topcoder forum thread for discussing about this. I want to improve them. Please share your opinions.

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7 years ago, # |
  Vote: I like it +45 Vote: I do not like it

Problems today are too bad. You don't need to think. You just need to code.

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7 years ago, # |
← Rev. 2   Vote: I like it +22 Vote: I do not like it

Is it rated?

UPD — Yes, it is.

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7 years ago, # |
← Rev. 2   Vote: I like it +34 Vote: I do not like it

I will write a simple editorial of Div.1 because the official editorial will post 10+ days later.

Div1 250pts
Div1 350pts
Div1 600pts


Code is here:

Div1 250pts
Div1 350pts
Div1 600pts
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7 years ago, # |
  Vote: I like it +79 Vote: I do not like it

cgy4ever Are you sure 600's test cases are valid? I failed systest on tc #17:

{{"......XX......", "..............", "....XX......XX", "........XX....", "....XXXXXXXX..", "....XX..XXXX..", "..XXXX..XXXX..", "XX............", "..XX....XXXX..", "XXXX........XX", "....XX..XX....", "..............", "............XX", "......XXXXXX.."}}

which is a 14x14 grid, which violates the constraints :(

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