We will hold AtCoder Beginner Contest 347.

- Contest URL: https://atcoder.jp/contests/abc347
- Start Time: http://www.timeanddate.com/worldclock/fixedtime.html?iso=20240330T2100&p1=248
- Duration: 100 minutes
- Writer: MMNMM, nok0, m_99, chokudai, Nyaan
- Tester: physics0523, kyopro_friends
- Rated range: ~ 1999
- The point values: 100-200-350-400-500-525-600

We are looking forward to your participation!

Good luck to everyone!

GLHF.

And let's have a guess!

Good Round :

Just so so Round :

Bad Round :

I hope I can stop dropping rated this round!

GL&HF.Hope my rating do not drop

My submission for problem C gives WA for only 1 testcase — LINK.

I can't figure out what's wrong in this,any help is appreciated.

same issue can anyone help

## include

## include

## include

using namespace std;

int main() { ios::sync_with_stdio(false); cin.tie(nullptr);

} this is my code

Wants more diverse presentation? Use Markdown.

ok

same issue dude, I missed both C and D today by just 1 test case each, which is the same test case as what you got wrong. I have no idea what could go wrong, spent 1 hr into debugging but of no use :(

Someone please help.

I think that the problem with your solution is that you didn't take into account that, even after first taking the remainder modulo $$$(A + B)$$$, the array can still be shifted for better adjustment.

To illustrate this with an example, try the hack:

2 5 5

1 7

The correct answer should be "Yes", but your solution outputs "No". The reason is, after taking the remainder, the array is still $$$[1, 7]$$$, but this gap of length $$$6 > A = 5$$$ between $$$1$$$ and $$$7$$$ means we can still shift the dates so that the first plan is on Day 5 and the second plan is on Day 11, which still works.

I reckon that anyone else failing to pass one or two test cases might be having this problem, too.

i also failed the same TC

Thanks，I have never thouht of that and WA on 01_test_28.txt

SpoilerAnswer should be yes.

was able to solve till E, what's wrong with 1 testcase in C? can anybody tell that testcase?

Yeah, I also couldn't get it AC because of this testcase.

same !

I'd like to know too. it's 01_test_28.txt case

same,my code also fails on it.

Here is my submission

I think the test cases are weak because I was also getting only 1 test case wrong for wrong solution.

C was annoying

Problem F is almost same with https://www.luogu.com.cn/problem/P3625

problem C ????????????

https://atcoder.jp/contests/abc347/submissions/51878189

where is this code going wrong ?? can anyone help . Thank you in advance

what was the last test case in problem D, I spent more than half hour but was unable to figure out that test case

D can be solved using DP.

AC Code

Thank you

https://atcoder.jp/contests/abc347/submissions/51845269

any help for C test case?

try this: 2 5 5 1 7

My approach to problem C was I calculated all days[i]%(a + b) then find the maximum and minimum in this array if then length is greater than a then its no otherwise yes but it did fail 1 test case IDK can somebody explain why is this approach wrong ! much appreciated

Do you know what the problem is with your solution because I have the same problem.

can somebody tell me why c is failing? I am checking if this below condition fails then it should be no: if(ar[i]%(a+b)>0 && ar[i]%(a+b)<=a) https://atcoder.jp/contests/abc347/submissions/51823167

i did the same, i guess we did not get the question right

yeah i guess.

You can actually pass F without considering those two cases:

If you comment those in the std you can still get an AC. Weak tests.

Does greedy not work for D?

https://atcoder.jp/contests/abc347/submissions/51871701

You need to apply one more check, that the numbers you have constrcuted have popcounts equal to a and b respectively, As for both num1 and num2 too you have constraint of being <2^60

Think of a case when a = 60 b = 60 and you have popcount of c = 60

In this case you will greedilly keep 30 1's in num1 and other 30 1's in num2, This will satisfy xor condition, but you don't have 60 popcounts in num1 and num2

it works https://atcoder.jp/contests/abc347/submissions/52433050

I must say problem C is very perfect

can u explain this please https://mirror.codeforces.com/blog/entry/127694?#comment-1141143

apologize for my impulse.

This comment was deleted.

an accepted submission

data:

ans: 80+77+74=231

my output is right while I did't pass the problem. The mentioned submission got wrong output.

In addition, the problem F is also the same as a problem in APIO2009. We found that the solution of that problem cannot be accepted in this. The problem link in a Chinese site.

I've just known that there's a problem of APIO which is almost the same as this one. I passed that problem.

...well, I hacked my submission just now. maybe the tests of F are weak but correct.

Good contest. Got 1 of WAs in C because got used to printing "YES" in cfs and atcoder requires 'Yes' :p

My pC also got 1 subtask WA at 01_test_28.txt ; Wondering what's the problem of my idea ; Actually I don't even think we need O(NlogN) to solve this ; Can't we just simply calculate the max and min value of D_i%(A+B) for all elements in D ; And consider the "max-min < A" one as "Yes" case?

lets say after doing modulo operation our array becomes 0 1 8 and a = 5, b= 5. basically we cant just rely on the the length of holidays we also have to factor in the days on which we can plan our events. in above tc max-min will give no. but if we think of today as day 4 then ans is yes

Tks bro you got the blind spot of my idea ヾ(･ω･*)ﾉ

hey man, can you please check my submission and let me know what is wrong thank you

can u explain this please https://mirror.codeforces.com/blog/entry/127694?#comment-1141143

What was C? I kept getting WA on 1 testcase, also I feel D>E.

My Solution for E !!

Can someone help me understand why my solution for C is wrong. Below is what I did.

i also did same, People are sorting the array, i think we didnt get the question. Can somebody explained what is the expectation of the problem?

For this test case

The answer is Yes but you output No

Understood. So basically the start day need not be the 1st day itself. Thanks.

I really Liked the Problem E,

My solution to E, using two sets

E SolutionCan anyone Give Counter Test for C https://atcoder.jp/contests/abc347/submissions/51861296 it is just falling on 2 test case

a possible hack for problem F:

the answer is 619.

(i1, i2, i3, i4, i5, i6) = (1, 2, 3, 1, 4, 4).

hey sorry to ask, can you please check my submission and let me know what i am doing wrong

only checking the maximum and minimum values is not enough.

your solution is far from the right one. suggest you do read the Editorial.

thanks man also don't stay alone

Can someone help me what's wrong with my E solution? It's AC for some tests but logic looks correct https://atcoder.jp/contests/abc347/submissions/51888633

Can someone explain me the C's editorial. I didnt get why we are subtracting ei+1- ei?

Can someone please help me find out where this code is failing for D? Submission Link

I think the testdata of F is kind of weak.

The solution mentioned 6 situations, but I didn't check the 1st and 4th (three submatrices on [left, mid, right], [top, mid, bottom]), still got AC.

My submission

(the array

`dp2[][]`

is useless)A hack data which my code can't pass:

Update: Here's what happened in my code.

Need help in debugging my code for problem D. My code fails on the last test case. Please help me in debugging, I'm not able to find any mistake. My Submission for D

nvm, found the mistake

Problem c was very annoying

SpoilerCan someone help me figure out why my code for problem C is failing , there's only 1 testcase that it didn't pass and I can't find a counter test case for my code.

According to my logic we reduce A[i] to A[i]%(a+b) at first , then we check for each Di how much we need to add in order for its mod with a+b to lie within [1,a] , based on this we'll get edges of an interval , if the interval is overlapping for all values of Di then I print yes , else no.

I also received 1 WA in C, but then I encountered an edge case where we can also create a cyclic schedule (which I hadn't considered during the contest).

1 WA Code...

int main() { ios_base::sync_with_stdio(false); cin.tie(NULL);

}

AC Code... int main() { ios_base::sync_with_stdio(false); cin.tie(NULL);

}

what's a cyclic schedule?

I mean you can imagine that as the subarray of plans which should have smallest length and fits in holiday schedule (You can make any day as starting point and see).

how to visualize total — plan[i] + plan[i — 1]?

Take an example a = 4, b = 3

Total Days: 1 2 3 4 5 6 7

so you can have holiday of length 4 (4 days)

Plans = 1 2 6

now as per my code

- you can say 1 as your first day of holiday so 1 2 3 4 here 6 is not included so it will not work

- now 2 as your first day of holiday so 2 3 4 5 this will also not work

- now 6 as your first day so 6 7 1 2, it is covering all plans so it is possible to do plan on this holiday window.

I hope you got the point.

got it thanks!!

Why I didn't take a look at PE... It turns out that PE was much easier than PC.

Mr. Takahashi, could you please add my ranking when I click on the Show favs only to filter the ranking list . So that we can compare with our good friends. Just like the Codeforces.

you should follow yourself

.

why checking only

`if(d[i - 1] + a + b - d[i] + 1 <= a){ flag = 1; }`

is sufficent ?what about the days at left of i-1 and to the right of i ?

how we will make sure that are also satisfied