We will hold Panasonic Programming Contest 2024（AtCoder Beginner Contest 354）.

- Contest URL: https://atcoder.jp/contests/abc354
- Start Time: http://www.timeanddate.com/worldclock/fixedtime.html?iso=20240518T2100&p1=248
- Duration: 100 minutes
- Writer: MtSaka, Aus21
- Tester: Nyaan, math957963
- Rated range: ~ 1999
- The point values: 100-200-350-450-475-525-625

We are looking forward to your participation!

Hope to ak!

Failed to solve G...

I think problem G is a bit hader than usual.

Actually some problem G's will be harder than yesterday's

I used a strange method to solve G, and it passed: It's a kind of "Hill Climbing" that can solve the "Weighted Maximum Independent Set Problem", but I'm not sure about its correctness. You can refer to my code for more details.

Who can hack it or analyze its correctness? Thank you.

how did you find Weighted Maximum Independent Set for a given graph ?

Just find the weighted maximum clique. And I used hill climbing to find it.

Hope to solve ABCDE, and one of F and G!

And, GL&HF(Good Luck and Have Fun)!

hope to solve ABCD!

Do you notice the problems can be read NOW???

UPD: i'm idiot, didn't notice the statements are not in this contest.Hope to solve ABCD, and E/F

有中国人吗？

Is there Chinese?

我是韩国人

有

有

有

有

Anyone who answered this question got -15, but 我是中国人。

swap D and E plz

+1

Problem

Fis similar to a variation ofDijkstra(computing edges on at least one shortest path), for which I recently created a practice problemI have also added hints for F on CF Step

D is created only to give pain and trauma :skull:

It was a great educational problem imo as I struggled for quite some time before landing on a fairly elegant solution. It seemed like a mess at first, but ended up being solvable by repeating a function 8 times which I liked.

CodeHi, I am new to Atcoder is it normal difficulty of a D problem in ABC? And after how much time does editorial comes out?

It is one of the most difficult D's I've ever seen. IMO, E and F were both miles easier than D today. Editorial takes a couple hours to a day to come out but there's usually a video editorial by evima for first 6 or all problems.

Evima editorial

Yeah I also felt was E easier, I should have skipped problem D. Thanks for help.

I saw geometry and skipped it. Lol, Ended up solving both E and F.

hi, did you solve it? can you share your code

I spent the majoirty of my time on it and never got it :sob

how to Memoize this solution ??? without memoization it gives a correct output

Could someone please explain the approach behind problem E to me? I tried using a queue to simulate all possible moves keeping track of available cards but it doesn't seem to be working

It's a standard dp on masks problem (The mask should store the removed cards)

Ohh!! I did use a mask to store which cards were used, but I used a queue instead of dp!! I guess replacing my queue operations with dp states will solve my problem. Thanks!!

We can discover that when the same card was removed, then the current player's possible move is same.

So we can just use a binary number to describe the set of cards that was removed and use another variable to store THE CURRENT PLAYER.

D without cancer casework how?

This is my solution,there is some casework but not much.

Probably there are simpler solutions, but to minimize the casework I implemented a function f(c, d) that computes the solution for rectangles with the origin (0, 0) as the bottom left corner and (c, d) as top right. Since the pattern is 4-periodic in both x and y shifting the rectangle by multiples of 4 does not change the answer. So I just shift everything to the top right quadrant (i.e. I make all coordinates a, b, c, d positive by adding multiples of 4) and then compute the solution using inclusion-exclusion as f(c, d) — f(a, d) — f(c, b) + f(a, b).

For the remaining blocks, suppose we cacluate from right to left, the pattern can be found if x and y is given: x % 4 and y % 2, there will be 8 cases for the start index.

You can check my video editorials of D, E, and F here

Solved both C and F using segment Trees. All I see is segment trees now :<

Can someone pls tell what is wrong with my E — https://atcoder.jp/contests/abc354/submissions/53637099 7 cases are failing

Missed F by 2 min because D took all my time.

CAN SOMEONE TELL WHY IS THIS WRONG FOR E , IM FRUSTATED## include<bits/stdc++.h>

using namespace std;

## define int long long int

## define endl '\n'

void solve(){ int a,b,c,d; cin>>a>>b>>c>>d; double arr[2][4]; arr[1][0]=0.5; arr[1][1]=1; arr[1][2]=0.5; arr[1][3]=0; arr[0][0]=1; arr[0][1]=0.5;arr[0][2]=0; arr[0][3]=0.5;

}

int32_t main() { ios_base::sync_with_stdio(0); cin.tie(0);cout.tie(0);

}

I can't read your code easily. Please write it in markdown.

here

What the things! You said this is problem E but this is problem D.

Upd:Stupid me! I've realized that it's not the issue in AtCoder. But I can still check your code.

what issue ? is my solution correct ?

Ok, I've found the approximiate wrong.

The probelm is that the basic rectangle(which is

`arr`

) can be shifted.This is the first time I've paticipated in AtCoder contest. Could someone please say, what is the approximate difficulty of the contest by cf standards?

i've only tried a, b, c and e i guess it would be

a-800

b-800

c-1300 or something like that

e-1600 or something like that

No, that's not what I meant. Is it like div2, div3, div1 + div2, etc.?

ABCs seem to be most similar to div3 I'd say.

I wouldn't agree with that. Normally I can solve all div3 problems without any special effort. As for AtCoder ABC, I can only solve 6 (out of 7) problems normally. And in approximately 50% of rounds I have no idea on how to solve G even after some time spent on it.

But if not div3 then what, div2? And since div3 last position problems are typically rated 2000-2300 from what I gather (and last div4 also had its last problem be of similar difficulty), they would match pretty well with the ABC difficulty curve you mention: most participants below CF yellow will reach but often not solve the hardest problem. :)

It's something between div2 and div3, but closer to div2 in my understanding, yes. Doesn't matter really, just wanted to show that to some people (like me) it seems more like div2 round, rather than div3.

thanks

you can say kinda div 2.5.

problem a and b are usually div. 4 a and b problem c is usually close to d2. C or d2. B d is like d2. c or d2. d and others followed.

ok, thanks

What is the idea behind G once the connection graph is built?

I suspect finding the largest antichain is somehow solved by decomposing into chains as per Dilworth's theorem through some max-flow/min-cut...

I spent soooooo much time on D!!!!!!!!!!! NOOOOOOOOOOO!!!!!!!!!! By the way, I think E is more difficult than F.So how do you guys solve E??

DP bitset

upd: E not use bitset, it can also AC. I can understand why so many people AC E now.

It is more stranger that the people solve E are 2223, D are 2092. D、F are quite a lot easy compare with E. D is quite easy by the way, but only 2092 people solve it. I doubt if some of them using

chatgptby solving probleE. I get AC of problem E using code generated by chatgpt 4o.why problem use priority_queue wrong?

`AC x6, WA x11`

Oh! I've ranked 28! I'm so happy!

I have felt practising topic wise is better for me as implementation speeds improves for me as i solve same topic in a row. But how to choose quality problems.

how do you choose problems to practise?

Why the problem C cant be solved using priority_queue

https://atcoder.jp/contests/abc354/tasks/abc354_c

please explain the issue in the logic

oh it was to be printed —

, in ascending order. Print these in the following format:

now i solved it

`D > E`

This time I solved problem F much faster than usual(maybe 15 minutes), because I have met a similar one, https://mirror.codeforces.com/contest/650/problem/D , during my virtual participation.

This makes me believe again that hard work will pay off sooner or later.

Can anyone help me to figure out that why my solution for Problem C is running locally but giving wrong answer on atcoder ? (I have also not used any global variables). "https://cl1p.net/code_c"

Can someone kindly breakdown G's solution for me?

My post contest discussion stream

Also, can someone hack my solution for G?

Gentle ping maroonrk because of this

I think problem D is not very good and I only solved ABCEF.

why Re

https://mirror.codeforces.com/blog/entry/70237

Thanks for the answer, it was solved perfectly

F is similar to https://www.spoj.com/problems/SUPPER/

Even the example is the same.

My classmate hzr hzr2023 got a good grade in this contest. but after the contest, He changed his country to the USA...

That picture of you is absolutely adorable！

how to solve bonus problem mentioned in F?

SummerSky mentioned the idea in his comment

There are 2 methods.

upd: E not use bitset, it can also AC. I can understand why so many people AC E now.

So many people solve

Ein the competition. I doubt if some of them usingchatgpt. I get AC of problem E using code generated by chatgpt 4o. The code is as follows.I think F needn't to use Segment Tree, Fenwick is okay. It only needs prefix maxminum.