Invitation to CodeChef January Lunchtime 2020

6

Here it is given only top 5 school students will get prizes ??
http://bit.ly/LTIME80-CodeChef-discuss

7

The link you’ve posted does not mention anything about prizes, so I’ll just assume you’re talking about Div2. Div2 has only 5 prizes, but @kingofnumbers is talking about Div1 where there are 10 prizes.

1 Like
8

Why 7:30 IST? Doesn’t it usually start at 9:30 IST? Plus it being a Saturday, that time would be more suitable to many.

9

there is a lot of variance between diff submissions in the tunnel question

all my c++ codes are getting wa on second subtaks where my python one passed easily…the logic is exact same.this led to me wasting a lot of time on this and then finally decided to do it again in python and I got ac…can anybody help on why the cpp one is giving wa?

@infinitepro

10

Lol, I tried debugging it myself (yes, I was stalking your submissions), but it’s not clear to me on why your code fails. Let me try it locally and get back to you!

2 Likes
11

I thought python mein tle karega so did first in c++…the exact opposite what happens in usual scenario

if this has not happened I might have done subtasks of the last 3 questions and maybe the third question completely

13

.

5 Likes
14

I thought lunchtime only measures rank by the score. I wasn’t sure, that it has panelty with wrong submission and re submition, i got Rank somewhat 2300+ very disappointed from my self. I f***ed up!

15

There is no penalty - but the time taken to reach the score matters.

1 Like
16

Nope.
Cook-off is at 9:30 on sunday
Lunchtime is at 7:30 on saturday.
I too agree with you that 9 to 12 would have been better. But maybe for school students 7:30 to 10:30 is better. Idk I am just guessing why codechef keeps it at 7:30.

1 Like
17

Oh i didn’t knew lunchtime had a syllabus ! But anyways tough problems are always better if you want to improve

18

There is no penalty with resubmission afaik.
Read rules below contest page.
They break ties by time taken to get AC.

19

so ioi problems are easier than standard/trivial matrix expo problems just wow.

do try the real ioi problems once and you will understand the difference.

20

u should not get disappointed by ur rank…

u should get disappointed by ur performance instead…

the penalty is cos u are late to reach score 200

first 2 were easy…i had very less time today and decided to spend 15 mins for contest

21

I’m so confused :sweat_smile: i have no idea about ioi, but that meme implied that

22

you have used a max heap in your c++ code which is wrong. python on the other hand has a minheap by default.

1 Like
23

@kharyusuf

1 Like
24

thanks totally forgot

25

Exactly! Nice catch.
@kshitij_789 You confused yourself with Dijkstra and DFS. You used a visited bool array like in DFS and used a heap (max heap) like in Dijkstra. This caused the problem, as once a vertex was relaxed, it wasn’t being relaxed again (even when a shorter path existed), leading to incorrect answers.

26

I remove that in contest see I had around 10 submissions.maybe you didn’t check the other ones.

problem was I used max_heap and used it like a min heap…
lesson learnt-do not overcomplicate bfs to djikstra

1 Like