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INOI 2018 discussion

How was INOI 2018? How much did u get? Also add ur scores to this spreadsheet.

asked 07 Jan, 17:07

mathecodician's gravatar image

accept rate: 7%

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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.


answered 07 Jan, 20:36

ista2000's gravatar image

2★ista2000 ♦
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?)


answered 08 Jan, 17:57

agniva_basak's gravatar image

accept rate: 0%

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

(08 Jan, 23:31) ista2000 ♦2★

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_basak2★

istapr0 is the codename

(09 Jan, 10:24) rajarshi_basu5★

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.


answered 07 Jan, 18:02

harishm17's gravatar image

accept rate: 14%

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


answered 07 Jan, 18:02

prajneya's gravatar image

accept rate: 0%

I got 200.

(07 Jan, 18:20) mathecodician5★

anyone solved 1 with bfs??


answered 07 Jan, 18:25

tanmay121's gravatar image

accept rate: 0%

What were the problems?


answered 07 Jan, 18:30

amit94's gravatar image

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...


answered 07 Jan, 19:02

kristopher's gravatar image

accept rate: 0%

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 ?


answered 07 Jan, 20:03

taksh001's gravatar image

accept rate: 0%

can anyone tell how to do the second question two paths


answered 07 Jan, 20:12

ssp547's gravatar image

accept rate: 26%

so what would be the expected cutoff??


answered 07 Jan, 21:15

tanmay121's gravatar image

accept rate: 0%

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

(08 Jan, 08:58) lokesh20024★

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_basu5★
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question asked: 07 Jan, 17:07

question was seen: 3,246 times

last updated: 28 Jan, 10:09