The Last Problem - Incorrect test data?

1

Does The Last Problem from the recent Cook-Off have wrong test data?

The constraints clearly mention that all coordinates are <= 1000 so I precomputed a grid of size 1004 * 1004:
https://www.codechef.com/viewsolution/46779159

That got WA for a very long time. I tried increasing my grid size and it passed…
https://www.codechef.com/viewsolution/46797516

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2

The value at cell (1000, 1000) is impacted by cell (2000, 0) as well. :wink:

So test data is correct.

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3

Ah okay, my bad. Didn’t realise this at all :frowning:

4

You can also precompute the grid without the (1000,1000) cell being affected by other cells more than it.
The idea is that the first number at ith row is s=(i*(i+1))/2. (sum of first i numbers) and all the consecutive numbers in that row’s columns are in AP s,s+i,s+i+(i+1) and so on

https://www.codechef.com/viewsolution/46782477

5

Same problem also happened with me. Now I realized the problem.

6

I tried this problem literally for the whole two and half hours of the contest time.

I thought the matrix in the question follows the Cartesian coordinate system, like x represents horizontal index and y represents vertical.

But to my surprise, after the contest has ended, I got to know from other solutions that my assumption was wrong and the x in the question meant to represent the vertical index and y for horizontal.

So, I just want to know if there is any convention that I am missing that would clear this out for me in future? or is the question flawed?