### atcoder_official's blog

By atcoder_official, history, 7 weeks ago,

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

We are looking forward to your participation!

• +50

 » 7 weeks ago, # |   0 250 for B will it be hard
•  » » 7 weeks ago, # ^ |   0 don't have such preconceptions on a difficulty of a problem based on points
•  » » » 6 weeks ago, # ^ |   0 exactly... I solved C but am stuck on B
•  » » » » 6 weeks ago, # ^ |   0 C is DFS,It's easy
•  » » » » » 6 weeks ago, # ^ |   0 https://atcoder.jp/contests/abc325/submissions/46831428 I lost 37 second.wuwuwu---
 » 6 weeks ago, # |   0 Just want to solve A... I'm to weak...
 » 6 weeks ago, # | ← Rev. 2 →   0 sfs
 » 6 weeks ago, # |   0 How to solve D ?
 » 6 weeks ago, # |   0 How to today's D? E was easier than D.
•  » » 6 weeks ago, # ^ |   0 is E a DP problem ??
•  » » » 6 weeks ago, # ^ | ← Rev. 2 →   0 I also tried with dp first,but it was modified dijktras
•  » » » » 6 weeks ago, # ^ |   0 What's the complexity of dijkstra approach?? Just curious
•  » » » » » 6 weeks ago, # ^ |   0 it is ElogV where E=O(N^2) and V=O(N)
 » 6 weeks ago, # |   0 problem C was the number of islands, it was a kind of standard graph problem.
 » 6 weeks ago, # |   0 I solved D, but couldn't solve E.
•  » » 6 weeks ago, # ^ |   0 can you explain your approach,E was modified djiktras. here is the code https://atcoder.jp/contests/abc325/submissions/46824003
•  » » » 6 weeks 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
•  » » » » 6 weeks ago, # ^ |   0 I was not sure if greedy would work :/ thanks..
•  » » » » » 6 weeks ago, # ^ |   0 I tried greedy and got 2 WAs.
•  » » » » » » 6 weeks ago, # ^ |   0 same -_-
•  » » » » 6 weeks 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?
 » 6 weeks 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
•  » » 6 weeks ago, # ^ |   0 Maybe you referenced $grid[n][m]$ where $n\ge N$ or $m\ge M$?
•  » » » 6 weeks 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
•  » » » » 6 weeks 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
•  » » » » 6 weeks ago, # ^ |   0 Just checked your code here and there, and resubmitted with sys.setrecursionlimit(500000). Got AC.
 » 6 weeks ago, # |   0 Can someone tell me what is wrong in my solution for problem D?
 » 6 weeks ago, # |   0 can someone tell what wrong in my solution for D https://atcoder.jp/contests/abc325/submissions/46827017
•  » » 6 weeks 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.
•  » » » 6 weeks ago, # ^ |   0 the multiset contains the range of unassigned point so which case is missed?
•  » » » » 6 weeks 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).
•  » » » » » 6 weeks ago, # ^ |   0 So the correct approach is also greedy right or two pointer?
•  » » » » » » 6 weeks ago, # ^ |   0 Right, greedy + PQ is correct. Greedy without PQ is incorrect.
•  » » » » » » » 6 weeks ago, # ^ |   0 my approach also passed just right sorting method was needed
 » 6 weeks ago, # |   0 can any one tell me what the topic of problem d?
•  » » 6 weeks ago, # ^ |   0 scheduling trick: pick the first-ending task use cp-handbook greedy section to learn about it
•  » » » 6 weeks ago, # ^ |   0 thank you bro (=
•  » » » 5 weeks 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 :|
 » 6 weeks ago, # |   0 How to solve $F$? I thought of dp but couldn't think how we gonna do it!
•  » » 6 weeks 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
•  » » » 6 weeks ago, # ^ |   +8 Thanks!tbh I misread constraints for $k$, assumed that $k \le 10^9$ :(
 » 6 weeks ago, # | ← Rev. 2 →   0 UPD: Never mind
 » 6 weeks ago, # |   0 ForbiddenREVEL_CSRF: tokens mismatch.
 » 6 weeks 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.
 » 6 weeks ago, # |   0 Don't know why but Dijikstar's didn't strike to me during the contest and i was bullish on Dp
•  » » 6 weeks ago, # ^ |   0 same ;(
 » 6 weeks ago, # |   0 Can anyone help me why this code is wrong for problem G? https://ideone.com/TZcGWP
•  » » 6 weeks ago, # ^ |   0 https://atcoder.jp/contests/abc325/submissions/46892400 My submission is also failing on 18 tcs
 » 6 weeks 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?
•  » » 6 weeks ago, # ^ |   0 Yes
 » 6 weeks ago, # | ← Rev. 2 →   0 My solution in problem D is almost the same as abc214_e
 » 6 weeks ago, # |   0 How to solve D? I solved E, but I can't solved D. Who can help me?
 » 6 weeks 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.
 » 38 hours ago, # |   0 .ComplaintFrame { display: inline-block; position: absolute; top: 0; right: -1.4em; } .ComplaintFrame a { text-decoration: none; color: #ff8c00; opacity: 0.5; } .ComplaintFrame a:hover { opacity: 1; } ._ComplaintFrame_popup p, ._ComplaintFrame_popup button { margin-top: 1rem; } ._ComplaintFrame_popup input[type=submit] { padding: 0.25rem 2rem; } ._ComplaintFrame_popup ul { margin-top: 1em !important; margin-bottom: 1em !important; } 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.