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INOI 2018 discussion

How was INOI 2018? How much did u get? Also add ur scores to this spreadsheet. https://docs.google.com/spreadsheets/d/1FiLaqTJDSm8E30UQWegIsuaJtvvdLlYAoqXyZMzK2dM/edit#gid=0

asked 07 Jan, 17:07

mathecodician's gravatar image

5★mathecodician
2.6k1830
accept rate: 7%


For second one, The observation was that, we can take one path and calculate the total sum without a second path using dp[i][j][k] = min/max(dp[i-1][j][k], dp[i-1][j-1][k-1])+prefix_sum[i][j]. We calculate this two times, once for min and once for max and then we can use the prefix sum intuition to subtract min-dp from max-dp. It's not clear enough here, but you might get an essence.

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answered 07 Jan, 20:36

ista2000's gravatar image

4★ista2000 ♦
2.4k621
accept rate: 20%

edited 07 Jan, 20:49

Exactly I did the same one but I made a error in finding dp(i)(j) and I didn't have time to debug so I couldn't get get partial in this so my ioitc hopes are down ,I am in 10th standard

(08 Jan, 09:30) lokesh20024★

There were two main insights:

  • The intersection constraint will implicitly be handled, since the base points have to be at least $K + 1$ apart.
  • You can represent a possible solution as the difference of two solutions which have the left region as the 0th column. (as you said, the prefix sum intuition)
(09 Jan, 12:30) animesh_f ♦6★

Oh boy , was the second problem hard to get a logic for then,in the center.Anyway I guess the first one was pretty easy ,just basic bfs (or if you prefer,DFS).The second one really took a lot of my time and still I could solve only the easiest subtast of it(the 3rd one only,k=0) and could actually also solve k=m-2 task if I had a little bit more time (enough to copy my code from ide to submit tab :( ) Anyway I don't think I would be able to qualify with a pretest score of 112 seeing these many people get more higher . Still hope the cutoff somehow comes out in my favour :P .(btw I thought in inoi they don't have scores based on class/grade in which the participants study in ,right?)

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answered 08 Jan, 17:57

agniva_basak's gravatar image

3★agniva_basak
212
accept rate: 0%

You might qualify if you are in class 10 or below.

(08 Jan, 23:31) ista2000 ♦4★

I am in 11th ,btw you gave exam in Kolkata center,right? I hoped to see you :P ,your questions in ico prep contests were pretty great.

(09 Jan, 09:46) agniva_basak3★
3

istapr0 is the codename

(09 Jan, 10:24) rajarshi_basu6★

My condition was similar. BTW am I the only one around here who use DSU on the first one? :P

(12 Jan, 22:00) dhruvsomani4★

I got 127 ... First one was a very easy dfs I found the 2nd question hard and did 2 subtasks in it.

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answered 07 Jan, 18:02

harishm17's gravatar image

1★harishm17
10018
accept rate: 14%

Solved the road trip and museum one. 100. Simple dfs. Couldn't solve the second one though. You?

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answered 07 Jan, 18:02

prajneya's gravatar image

2★prajneya
2
accept rate: 0%

I got 200.

(07 Jan, 18:20) mathecodician5★

anyone solved 1 with bfs??

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answered 07 Jan, 18:25

tanmay121's gravatar image

4★tanmay121
1
accept rate: 0%

What were the problems?

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answered 07 Jan, 18:30

amit94's gravatar image

2★amit94
662
accept rate: 25%

I solved the first one using BFS and got 100... For the second one I used prefix sums and got 12 points...

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answered 07 Jan, 19:02

kristopher's gravatar image

4★kristopher
383
accept rate: 12%

I kept getting Segmentation error and runtime error while solving the first question. When I decreased the changed the adj list from adj[1000005] to adj[1005], the code ran fine.

Did anyone else have this problem ? Also, what was I doing wrong ?

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answered 07 Jan, 20:03

taksh001's gravatar image

3★taksh001
0
accept rate: 0%

can anyone tell how to do the second question two paths

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answered 07 Jan, 20:12

ssp547's gravatar image

4★ssp547
3077
accept rate: 25%

so what would be the expected cutoff??

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answered 07 Jan, 21:15

tanmay121's gravatar image

4★tanmay121
1
accept rate: 0%

148 for 11,12 and 100 for 10 and below i guess

(08 Jan, 08:58) lokesh20024★
1

I think it would be 112 for 10th and below else too many people would qualify.

(08 Jan, 11:33) mathecodician5★

116 overall. I dont think they should make separate cutoffs.

(09 Jan, 10:25) rajarshi_basu6★

are the cut-offs different for 10th and below and 11th and 12th. I am in 9th and getting 100 what are my chances of getting into the TC.

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answered 08 Jan, 10:22

ssp547's gravatar image

4★ssp547
3077
accept rate: 25%

Are there any chances that cut off for 10th and below will fall to 100

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answered 08 Jan, 16:19

ssp547's gravatar image

4★ssp547
3077
accept rate: 25%

I got 100 - solved the first question. I noticed the k=0 subtask way too late for the second one. I didn't have time to implement it properly :/

I'm really hoping that the cutoff for 10 and below is 100, but seeing the number of people who've got a score >100, I doubt that's going to happen :(

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answered 08 Jan, 21:44

benritmico's gravatar image

4★benritmico
1
accept rate: 0%

Do anybody know when the results will be published??

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answered 08 Jan, 22:09

ssp547's gravatar image

4★ssp547
3077
accept rate: 25%

The results will be mostly announced within 10 days of INOI...

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answered 12 Jan, 15:53

kristopher's gravatar image

4★kristopher
383
accept rate: 12%

@kristopher, are you sure? I hope they release it quickly. :)

(12 Jan, 21:58) dhruvsomani4★

Can someone please remind me what the subtasks of the problem Two Paths were, and how many points each of them was worth? Thanks..

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answered 12 Jan, 23:25

architb12's gravatar image

3★architb12
1
accept rate: 0%

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answered 16 Jan, 22:45

ssp547's gravatar image

4★ssp547
3077
accept rate: 25%

and i got qualified, hope you all get qualified too, best wishes:)

(16 Jan, 22:54) ssp5474★

I am a class 10 student and I got 112 during the contest. I did not qualify INOI. Guess why ? My code failed in system test of problem 2 because of a blunder mistake in my code . I typed row variable instead of column variable while calculating the result in the last step of my code. I failed to realize it during the contest because my code passed the given test cases and I never thought of re-checking it. As a result I got 100 and did not qualify INOI :(

(Though I got 76.5/80 in Sanskrit exam which was on day before INOI and I got 76/80 in Social Science exam which was on day after INOI . I really have to manage between school and competitive programming because of ... )

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answered 26 Jan, 20:19

onkarnandedkar's gravatar image

4★onkarnandedkar
313
accept rate: 0%

Can someone share how they prepare for INOI and competitive programming in general

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answered 26 Jan, 20:35

aloo1304's gravatar image

2★aloo1304
211
accept rate: 0%

See the interview by Rishik Sood on the Codechef blog.

(26 Jan, 22:13) dhruvsomani4★

Can someone share problems statement?

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answered 27 Jan, 19:20

ioi2018's gravatar image

5★ioi2018
1
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question asked: 07 Jan, 17:07

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last updated: 28 Jan, 10:09