forgotter's blog

Google FooBar challenge
By forgotter, history, 5 years ago, In English

My friend one_punch recently shared a Google foobar challenge referral with me. I've completed most levels of it and really liked few of those questions. (We can talk more on questions separately). Now, I myself have two more referrals to invite others.

I have come up with idea that interested people (cf users) can fill up a form, so I could have a list of interested peoples. I'd sort the list in decreasing order of rating and one by one invite most of them.

With only two referrals, how can I invite everyone? After I send a referral to someone (on list), that person would send me one (new) referral back and I will again be left with two referrals and this can keep going on until the list is exhausted or someone doesn't sends back a referral.

Something about challenge:
Total levels : 5
Total questions : 1+2+3+2+1
Language : Java/ Python 2.7 (yes,it sucks!)
A referral is given after completing of level 2 and level 4.
After completing level 3, you'll be asked for your details to share with a recruiter.

Estimated difficulty:
Level 1: Div 2A
Level 2: Div 2B
Level 3: Div 2D
Level 4: Div 2E
Level 5: Haven't solved it yet.
One might get easier or difficult questions depending upon their luck.

Please fill up this form before May 1, 12p.m. IST. https://forms.gle/NyevAC5NPXvS8y6s5

P.S. If anyone has any suggestion to make, you're welcome:)

P.P.S. I've started sending the invite as per above mentioned order. I'm sending it as codeforces message. (It might take some time for your turn to come, so please wait till then.)

Update: The list conatins 166 people. On average, the referral passes through 4 people in a day (So please try to be quick, when it's your turn). You also encouraged to try out ways to trigger the invitation (search google). Click here to generate a new invite. Thanks to temp481 for providing the link.

Re: Generator website is down. As suggested by hydro_lyte, Triggering it with known keywords can give you invitation. Search for "c++ move semantics" 2-3 times and you will receive an invitation.. "Java Arraylist" is also a known search keyword, you can try your luck. I hope most of you manage to get it without waiting for your turn in the queue.

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Comments Comments (37)
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5 years ago, # |
  Vote: I like it +8 Vote: I do not like it

Codeforces handle is accepting only number in google form. Please correct it

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5 years ago, # |
← Rev. 2   Vote: I like it 0 Vote: I do not like it

I also have referral for foobar challenge.

Edit : I activated it myself but one can activate by other means also here is a codeforces article explaning what they did https://codeforces.net/blog/entry/50841

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

    Is it still available? If Yes would you refer me?

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5 years ago, # |
  Vote: I like it +16 Vote: I do not like it
Language : Java/ Python

Damn. Why Google, why not C++?

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5 years ago, # |
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Auto comment: topic has been updated by forgotter (previous revision, new revision, compare).

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5 years ago, # |
← Rev. 2   Vote: I like it +10 Vote: I do not like it

According to me.

Estimated difficulty: Level 1: Div 2A

Level 2: Div 2A-Div 2B

Level 3: Div 2B-Div 2C

Level 4: Haven't solved it yet.

Level 5: Haven't solved it yet.

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    5 years ago, # ^ |
      Vote: I like it +5 Vote: I do not like it

    Depends on luck!

    I got a DP with BFS, one Gaussian Inversion and one Greedy (Number Theory) at level 3. Is it still the same level?

    A friend got a question from Flow on level 4. He got other problems easy tho (Haven't discussed all problems yet as we're still solving the last one). I got some weird bitmask dp over graph (Maybe I over-complicated it).

    Nvm, the questions seemed interesting and it was fun solving them.

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    5 years ago, # ^ |
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    I got a medium level BFS , a medium level dp and a difficult to implement greedy problem in level 3. All level-3 problems were definitely harder the div2-c. Looks like I got a tough set :\

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5 years ago, # |
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Auto comment: topic has been updated by forgotter (previous revision, new revision, compare).

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

After log in with a referal, how much time I have before the referal get expired? Before sending a request command?

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

    You should log in with your id once you're on challenge page. This will save your state and you can resume later.

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

      I want to know how much time I can resume. Like I logged in. I want to start the challeges after about a month. I haven't started the contest. Thank You.

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        5 years ago, # ^ |
          Vote: I like it +3 Vote: I do not like it

        I have no clue about it. Although, I can tell you about time (approx.) you get to complete a challenge, maybe you can use it somehow.

        Level 1: 1 Question: 3 days
        Level 2: 2 Questions: 5 days for each
        Level 3: 3 Questions: 7 days for each
        Level 4: 2 Questions: 14 days for each
        Level 5: 1 Question: 21 days

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5 years ago, # |
  Vote: I like it +9 Vote: I do not like it

Well, there's a better way to access foobar: foobarinvite

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    5 years ago, # ^ |
      Vote: I like it +1 Vote: I do not like it

    Wow, thanks a bunch man. Now, everyone will be able to get it without further wait. I'm adding it to post and giving you credits for discovering this.

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5 years ago, # |
  Vote: I like it +15 Vote: I do not like it

Triggering it with known keywords can give you invitation. Search for "c++ move semantics" 2-3 times and you will receive an invitation.

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

    Since website is down, I'm adding your suggestion to the post so others can get an invite without waiting for the their turn in the long long ... queue.

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5 years ago, # |
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Auto comment: topic has been updated by forgotter (previous revision, new revision, compare).

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

Auto comment: topic has been updated by forgotter (previous revision, new revision, compare).

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5 years ago, # |
← Rev. 2   Vote: I like it -11 Vote: I do not like it

How can I send someone a referral if I got in the challenge?

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    5 years ago, # ^ |
      Vote: I like it +9 Vote: I do not like it

    It means that some of the classes u used are actually prohibited to use.

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

    You can message the link to me and I'll use it along with other invites to invite them who are still in queue.

    Thanks.

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5 years ago, # |
← Rev. 3   Vote: I like it +8 Vote: I do not like it

I'm not sure if I just got lucky, but all of the questions I got weren't super difficult. Here are my thoughts on the problems:

Level 1: Brute force (Div2B)

Level 2: Both implementation (Div2B)

Level 3: Trivial DP (Div2C), number theory (Div2D), and constructive algorithm (Div2C). The second and third both required BigInteger, so I'm not sure if this would inflate their difficulty

Level 4: Bellerman Ford + Bash (Div2D) and constructive (Div2E)

Level 5: Bitmask dp (Maybe Div2E? Leaning more towards Div2D)

I managed to finish all of these problems in a day, with the bulk of my time being spent on the constructive problem on Level 4. Please note this is not supposed to be a flex in anyway, I'm just trying to offer my opinion on the equivalent cf difficulty for each problem I got.

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

    I used Python int for the BigInteger ones, and expected TLE, but somehow it passed.

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

I also have a spare link, please add yourself to the queue here, at rudradesai.in/cfviewer. For more info, please read this blog here.

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5 years ago, # |
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Anyone know why i keep getting BLACKLISTED_CODE when i try to verify the solution?

I don't use java much so i ended up copy pasting a few imports, set initializations etc.. Is that not allowed? I tried rewriting the code from scratch, it didn't work. Then I tried searching it up and the only webpage I found regarding that matter was a chinese page with 1 reply. It's almost like noone has faced this problem or like is it intentionally hidden? Idk its kinda wierd

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    5 years ago, # ^ |
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    Some specific classes are not allowed.

    Also, import only those classes which are needed, do not use statements with wildcards like :

    import Java.util.*

    Instead import using:

    import Java.util.LinkedList

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      5 years ago, # ^ |
      ← Rev. 2   Vote: I like it 0 Vote: I do not like it

      Initially it was import java.io.* and import java.util.io*

      I tried changing them to import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; and its still blacklisted code

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        5 years ago, # ^ |
        ← Rev. 2   Vote: I like it 0 Vote: I do not like it

        I don't think you need input/output for any foobar challenge. What are you using it for? All input is given through function argument and all output must be returned by the function as specified.

        Edit: I found an article stating input/output operations are not allowed in the challenge, probably must be mentioned in their rules too.

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          5 years ago, # ^ |
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          You're right, Why didn't I realize that lol.

          Thanks dude.

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5 years ago, # |
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I have completed the challenge and made this Github repository to share my experience on the challenge. Check it out if you are interested

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4 years ago, # |
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I got it in one search "c++ move semantics",

but python and java :(

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