### atcoder_official's blog

By atcoder_official, history, 10 months ago,

We will hold KEYENCE Programming Contest 2023 Autumn（AtCoder Beginner Contest 325）.

We are looking forward to your participation!

• +50

 » 10 months ago, # |   0 250 for B will it be hard
•  » » 10 months ago, # ^ |   0 don't have such preconceptions on a difficulty of a problem based on points
•  » » » 10 months ago, # ^ |   0 exactly... I solved C but am stuck on B
•  » » » » 10 months ago, # ^ |   0 C is DFS,It's easy
•  » » » » » 10 months ago, # ^ |   0 https://atcoder.jp/contests/abc325/submissions/46831428 I lost 37 second.wuwuwu---
 » 10 months ago, # |   0 Just want to solve A... I'm to weak...
 » 10 months ago, # | ← Rev. 2 →   0 sfs
 » 10 months ago, # |   0 How to solve D ?
 » 10 months ago, # |   0 How to today's D? E was easier than D.
•  » » 10 months ago, # ^ |   0 is E a DP problem ??
•  » » » 10 months ago, # ^ | ← Rev. 2 →   0 I also tried with dp first,but it was modified dijktras
•  » » » » 10 months ago, # ^ |   0 What's the complexity of dijkstra approach?? Just curious
•  » » » » » 10 months ago, # ^ |   0 it is ElogV where E=O(N^2) and V=O(N)
 » 10 months ago, # |   0 problem C was the number of islands, it was a kind of standard graph problem.
 » 10 months ago, # |   0 I solved D, but couldn't solve E.
•  » » 10 months ago, # ^ |   0 can you explain your approach,E was modified djiktras. here is the code https://atcoder.jp/contests/abc325/submissions/46824003
•  » » » 10 months ago, # ^ |   0 For D, I put all eligible candidates in a priority queue and then pick one which is the earliest to finish: https://atcoder.jp/contests/abc325/submissions/46822856
•  » » » » 10 months ago, # ^ |   0 I was not sure if greedy would work :/ thanks..
•  » » » » » 10 months ago, # ^ |   0 I tried greedy and got 2 WAs.
•  » » » » » » 10 months ago, # ^ |   0 same -_-
•  » » » » 9 months ago, # ^ | ← Rev. 2 →   0 Why the one earliest to finish? We can choose the one earliest to enter as well. Can you please explain in a bit detail?
 » 10 months ago, # | ← Rev. 3 →   0 For problem C, why does it not work if I do not use a visited set? It should be sufficient to mark it as empty "." right? Is there an edge case i am missing here?https://atcoder.jp/contests/abc325/submissions/46818827
•  » » 10 months ago, # ^ |   0 Maybe you referenced $grid[n][m]$ where $n\ge N$ or $m\ge M$?
•  » » » 10 months ago, # ^ |   0 if r<0 or r>=n or c<0 or c>=m or grid[r][c] == ".": returnI have this check in the dfs function to ensure I am not referencing that
•  » » » » 10 months ago, # ^ |   0 oh... turns out the solution is to add this line for python :(import sys sys.setrecursionlimit(10**6)https://atcoder.jp/contests/abc325/submissions/46833195
•  » » » » 10 months ago, # ^ |   0 Just checked your code here and there, and resubmitted with sys.setrecursionlimit(500000). Got AC.
 » 10 months ago, # |   0 Can someone tell me what is wrong in my solution for problem D?
 » 10 months ago, # |   0 can someone tell what wrong in my solution for D https://atcoder.jp/contests/abc325/submissions/46827017
•  » » 10 months ago, # ^ |   0 You have to use a priority queue. Imagine when you are at time t, and there are two segments which contain t. At this point, it doesn't matter which of these segments begins first. All it matter is which of these segments finish first.
•  » » » 10 months ago, # ^ |   0 the multiset contains the range of unassigned point so which case is missed?
•  » » » » 10 months ago, # ^ |   0 Not sure, but the WAs in your submission are exactly the same as mine when I tried using greedy: https://atcoder.jp/contests/abc325/submissions/46811464So, your approach has the same outputs as my greedy approach (which has 6 WAs).
•  » » » » » 10 months ago, # ^ |   0 So the correct approach is also greedy right or two pointer?
•  » » » » » » 10 months ago, # ^ |   0 Right, greedy + PQ is correct. Greedy without PQ is incorrect.
•  » » » » » » » 10 months ago, # ^ |   0 my approach also passed just right sorting method was needed
 » 10 months ago, # |   0 can any one tell me what the topic of problem d?
•  » » 10 months ago, # ^ |   0 scheduling trick: pick the first-ending task use cp-handbook greedy section to learn about it
•  » » » 10 months ago, # ^ |   0 thank you bro (=
•  » » » 9 months ago, # ^ | ← Rev. 2 →   0 Not exactly the same problem... if i recall the one in cph disallows choosing another task whilst performing the first one, so the proof for this problem is different from in CPH. However its true the greedy is the same.Seems like the proof is a bit difficult... wonder why they omit it in the editorial :|
 » 10 months ago, # |   0 How to solve $F$? I thought of dp but couldn't think how we gonna do it!
•  » » 10 months ago, # ^ | ← Rev. 2 →   +5 $dp_{i, j} = \min$ number of type-2 sensors to cover first $i$ ranges if we also use $j$ type-1 sensors
•  » » » 10 months ago, # ^ |   +8 Thanks!tbh I misread constraints for $k$, assumed that $k \le 10^9$ :(
 » 10 months ago, # | ← Rev. 2 →   0 UPD: Never mind
 » 10 months ago, # |   0 ForbiddenREVEL_CSRF: tokens mismatch.
 » 10 months ago, # |   +3 I think problem F is very inspiring, even though I didn't come up with that definition as the editorial mentions.However, this reminds me of a problem that I have met before, which involves a similar idea https://codeforces.com/contest/745/problem/E.When I first met some new ideas, I could keep that in mind, maybe for several days, and this time, it shows again that, I will forget it sooner or later. I think I should practice harder and more.
 » 10 months ago, # |   0 Don't know why but Dijikstar's didn't strike to me during the contest and i was bullish on Dp
•  » » 10 months ago, # ^ |   0 same ;(
 » 10 months ago, # |   0 Can anyone help me why this code is wrong for problem G? https://ideone.com/TZcGWP
•  » » 9 months ago, # ^ |   0 https://atcoder.jp/contests/abc325/submissions/46892400 My submission is also failing on 18 tcs
 » 9 months ago, # |   0 Could someone expain me this sentence?You can switch from company car to train, but not vice versa. You can do so without spending time, but only in a city.Does that mean once I get on the train,I can't get on the car anymore,then I must get to the n city by train?
•  » » 9 months ago, # ^ |   0 Yes
 » 9 months ago, # | ← Rev. 2 →   0 My solution in problem D is almost the same as abc214_e
 » 9 months ago, # |   0 How to solve D? I solved E, but I can't solved D. Who can help me?
 » 9 months ago, # |   0 Can anyone please explain D to me in detail? Why are we not taking the start time first and all that? I am really struggling with this problem and I also didn't find the editorial of much help. Any explanation would be really highly appreciated.
 » 8 months ago, # |   0 can anyone tell me why the 3rd test case of problem B is 67 and not 66? My manual calculation gives 66. But I can't understand how it is 67.