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[closed] Extremely weak test cases in JULY 16 CHEFTET

Though I have not yet started this contest, one of my roommates was doing this question , and by an extremely wrong approach got full 100 marks , and I was left astounded .

If I am allowed to reveal , then I can mention some test cases where many submissions will fail if they are using same logic as of my roommate .

It is my request to admin as well as tester to please look into the matter , and rejudge the solutions.

Edit :- Thanks a lot admin and tester for changing the test cases :) . Also , I couldn't understand why many people downvoted this post :P

asked 02 Jul '16, 23:37

shivamg_isc's gravatar image

accept rate: 0%

closed 09 Jul '16, 17:17

kcahdog's gravatar image



After 3 days of this post Codechef should have done something, but still I cannot see any changes in the problem statement or rejudgement of solutions.

(06 Jul '16, 14:37) dl20505★

@admin assured us that he will look into the matter . I doubt the cases will be changed now .

(06 Jul '16, 18:06) shivamg_isc5★

So , is your roommates's solution still accepted ? :P

(08 Jul '16, 23:12) shubham992★

no .. not yet :P

(08 Jul '16, 23:35) shivamg_isc5★

The question has been closed for the following reason "The question is answered, right answer was accepted" by kcahdog 09 Jul '16, 17:17


Well, why were you discussing the ongoing contest problem with your room mate though? You accept that you did not abide by CoC? :P :P :P


answered 03 Jul '16, 22:07

lohit_97's gravatar image

accept rate: 4%


Lol . That was not discussion bro . He was highly ecstatic when his solution of CHEFTET was accepted within 10 mins of solving the 2nd question , and he told me the approach , and said how dumb the question was and unnecessarily the language was made hard . I had seen the question the previous day and had another approach in mind , and that is why when he told me the approach , I figured out several test cases where that solution is bound to fail :) And now he is mad at me xD

(04 Jul '16, 12:19) shivamg_isc5★

Well, yeah, the cases are really weak. A two line solution of mine passed.

(05 Jul '16, 18:29) lohit_974★

question is not clear as, is it must that all Bi's must fall on array A or some can remain? . I took the question to be,"Some Bi's can remain in the array B" and got accepted. In fact the the complexity is O(n) and i can't understand why limits are n<10000.


answered 03 Jul '16, 00:00

vamsi_deva's gravatar image

accept rate: 0%

I also interpreted the question this way and got AC.

(03 Jul '16, 17:45) noble_mushtak5★

@admin So, what is it finally, do we have to use all the elements of b? And can we use the same element of b multiple times?


answered 08 Jul '16, 16:17

akulgoel96's gravatar image

accept rate: 12%

edited 08 Jul '16, 16:31


My solution assumes we have to use all elements of b and passes.

(08 Jul '16, 20:43) c1_66★

So, can we use elements of b multiple times?

(08 Jul '16, 22:04) akulgoel963★

no u need to use each element only once...some subtasks failed because of that

(09 Jul '16, 03:32) atulshanbhag4★

I solved the question by O(4*n), and the code is not short. Unbelievable, there are many people got AC by the wrong algorithm, and with only 2 line code?! I was so sad to know about that. QwQ


answered 04 Jul '16, 05:09

nano_ape's gravatar image

accept rate: 0%

by telling the complexity, you kinda revealed the entire algorithm :P

(09 Jul '16, 16:37) prrateekk3★

Then this particular problem should be rejudged!! After the updation of the testcases.


answered 03 Jul '16, 14:55

tejaram15's gravatar image

accept rate: 0%

I even commented this on the problem statement page, whether or not all B[i] have to be used and as you can expect no admin, setter, tester replied. This is sad, problem statement is not clear :(


answered 04 Jul '16, 09:10

ashwanigautam's gravatar image

accept rate: 0%

Yeah definitely the problem statement is so milsleading that it took me 20 submissions to get AC and that too after referring this blog post. Thanks!! I dont know how both the problem setter and tester didnt notice the fault in the problem statement.


answered 04 Jul '16, 16:29

akshayv3's gravatar image

accept rate: 4%

Well , this was a disaster , first I have to assume that some element from B can remain in B . Thanks to this thread . Second , I have to assume that we can use same element of b multiple times . Since it is once in a blue moon mistake by tester and author so no offence to codechef .


answered 07 Jul '16, 14:52

rajan_parmar's gravatar image

accept rate: 0%

edited 07 Jul '16, 14:56

thanks rajan for information.. but why not codechef clear this according to question B will fall on A in this scenerio one element of B can fall on unique element of A so that element of B can't be reused.... such type of information less question kills time this is really irritating..

(08 Jul '16, 23:10) rohitangira3★

@vamsi_deva I didn't know that . My roommate used all of A[] and B[ ] , and with 2 line code got it AC . And now comes storm of downvotes :P


answered 03 Jul '16, 00:04

shivamg_isc's gravatar image

accept rate: 0%

Two lines? Seriously? :O No wonder so many users solved it.

(03 Jul '16, 07:30) pranavarora6★

I will share the submission once the contest will be over :P , and in case they don't change the cases , I am sure this will be disaster . @admin please look into this

(03 Jul '16, 12:35) shivamg_isc5★

Damn please do share that 2 line code later :P

(03 Jul '16, 22:12) sanket4074★

hahahaha :P sure . I meant the implementation part bdw xD

(03 Jul '16, 22:31) shivamg_isc5★

if(sum % n == 0 && (sum/n == a[0] || sum/n == a[0] + b[0] || sum/n == a[0] + b[1] || sum/n == a[0] + b[0] +b[1])) printf("%lld\n",sum/n); else printf("-1\n");

^these were those 2 lines, which got 100. :P

(13 Jul '16, 18:36) xariniov96★

This was the 2 lines of code of my roommate giving 100 :P

(13 Jul '16, 23:42) shivamg_isc5★
showing 5 of 6 show all

This happens often here. They should add new test cases or else problem has no meaning.


answered 03 Jul '16, 07:00

apptica's gravatar image

accept rate: 17%

@apptica Exactly , it seems as if the problem was meant to be cakewalk .

(03 Jul '16, 12:45) shivamg_isc5★

Hi @apptica, we will take a look into this complaint and take necessary action very soon. Thanks for notifying.

(03 Jul '16, 13:41) dpraveen ♦♦4★

Its ok as i know that you will fix the problem soon. This is what i like about codechef the most :)

(03 Jul '16, 22:45) apptica5★

This guy deserves a medal! :P


answered 03 Jul '16, 15:46

himanshu_m's gravatar image

accept rate: 0%


hahahha :P ...only if they change the test cases :P

(03 Jul '16, 15:49) shivamg_isc5★

I wish Codechef had strict test cases like Codeforces...even easier questions would be challenging


answered 03 Jul '16, 16:03

prrateekk's gravatar image

accept rate: 12%


and I wish codechef had open hacks like educational rounds :D

(03 Jul '16, 16:34) killjee5★

Can someone tell me output for second problem of july challenge for following test case
1 5 6 8 10 14 16 19 20 25 28 30 35 36 40 45


answered 03 Jul '16, 19:42

akatel's gravatar image

accept rate: 0%


This is not a place to ask this question , and moreover this is an ongoing contest . You have to figure it out yourself.

(03 Jul '16, 19:44) shivamg_isc5★

This guy is new on codechef . You guys could have told him this without the downvotes. I dont think this is a good way to welcome somone to the community.

(04 Jul '16, 00:10) shubham992★

I made a function solve(), which was empty back then, and tried to submit it, and GOT AN AC! :P I even commented on the problem. The problem is ambiguous, a lot of things are unclear!


answered 03 Jul '16, 21:10

sahilarora.535's gravatar image

accept rate: 0%


I hope they either update the problem statement or change the test cases soon.

(03 Jul '16, 21:52) shivamg_isc5★

Mail codechef about this and they may update the test cases as they have done a few times earlier :)....your roommate will be surely mad at you :P


answered 04 Jul '16, 02:36

anuraag_s2's gravatar image

accept rate: 0%

@ashwanigautam I too have asked this question 4 days ago in problem statement page and have tagged the admin and the author. Inspite of all that no reply yet.


answered 04 Jul '16, 10:33

vamsi_deva's gravatar image

accept rate: 0%

If more test cases is added it should be done as soon as possible, so there is time left to submit a new correct solution, in case one's approved solution is invalid.


answered 04 Jul '16, 19:49

tony_hager's gravatar image

accept rate: 0%

Also the explanation for the second example case is wrong. I mentioned it in a comment 2 days ago but the comment hasn't been published nor has the example been fixed. I would fix it myself if I could.


answered 04 Jul '16, 20:25

luc4sdreyer's gravatar image

accept rate: 10%

edited 04 Jul '16, 20:26

@admin test cases for 25 point for chefarc are really weak.I can provide you test cases on which my code should give WA but still works on yours :)


answered 06 Jul '16, 04:10

h_trap's gravatar image

accept rate: 0%

For partial points , the test cases may be weak . OK , many will be fine with it , but for 100 ??? Are you kidding me? -_-

(06 Jul '16, 18:08) shivamg_isc5★

2 lines code logic!! I wonder what those lines could be...


answered 06 Jul '16, 14:01

bhushi_007's gravatar image

accept rate: 0%

Hahahhaa :P You don't have to wait too long . 5 more days to go xD

(06 Jul '16, 18:07) shivamg_isc5★

Even I commented the same on the problem statement page along with a test case. I have even figured out the probable test cases set by the admins of this particular problem. No response received yet on my comment.


answered 06 Jul '16, 17:04

codeslayer1's gravatar image

accept rate: 0%

Will the test cases be ever updated I don't know what's talking so long. It would be really helpful if you update test cases ASAP as if one's solution fail he can review and resubmit his code not like a LTIME where testcases were updated after the contest.


answered 06 Jul '16, 20:10

killjee's gravatar image

accept rate: 5%

edited 06 Jul '16, 20:11

please clarify the JULY CHALLENGE problem 02 , test case number 2.


answered 06 Jul '16, 21:38

adicodechef_02's gravatar image

accept rate: 0%

So it seems they added new test cases:-

08/07/2016, 1234 hrs IST: Test data of problem CHEFTET was weak. We have put all the submissions for rejudge. Please resubmit your solution if you are affected by it. We really regret the inconvenience.

Thankfully my solution wasn't affected.


answered 08 Jul '16, 15:15

c1_6's gravatar image

accept rate: 0%

Now anybody tell me that can B contain some elements at the end ?


answered 08 Jul '16, 19:49

amanpreetsingh's gravatar image

accept rate: 0%

wikified 08 Jul '16, 19:56

no all B elements must fall... that is why i got wrong too

(09 Jul '16, 03:36) atulshanbhag4★

The problem statement should be updated There is too much confusion about whether B can retain some elements or if the same element can be used multiple times. Else it is not clear.


answered 08 Jul '16, 20:44

rajarshi_basu's gravatar image

accept rate: 10%

In the problem statement of CHEFTET its written that:- "array B is falling on array A, such that number Bi is directly above the number Ai initially." "If element Bi falls on Ai, Ai gets increased by Bi." So that means Bi must fall on Ai then only Ai increases and if Bi falls on any of Ai-1 or Ai+1 then it doesnt increases as per problem statement but in test case no 2 last both 10's are falling on same number 1. What does that means will anyone tell me.??


answered 09 Jul '16, 12:23

puper_fused's gravatar image

accept rate: 0%

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question asked: 02 Jul '16, 23:37

question was seen: 10,061 times

last updated: 13 Jul '16, 23:42