As a tester, problems are very interesting!

As a tester, I can assure you that the problemset is interesting, and the round will be enjoyable.

cry disappeared

As a tester, you will enjoy solving the problems..

why isn't there any grey(gray) testing of the round considering its div3?

Finally

Finally excited for my first unrated contest

Yes, I’m ready to be back to CYAN, inshaAllah!

I'll try imitate rainboy in this round.

As a tester, problems are very interesting!

hopefully my journey of ending failure will start from this contest

I am excited to participate with my new monitor set-up today..!

Why did this dude TrinhTranPhuongTuan banned? Cause he got top 1???

In G are the sample testcases correct?

first time ak div3! ヾ(^∀^)ﾉ

Perfecto

I am never writing a div3 or div4 again.

Although i didn't participate in this round, i've read the problems and i think it is one of the best div3s i remember

The hardest div3 I have ever seen(for me)... can't solve G, get plenty on C E and F stuck on B for 10min, F for 1 hour, I'm too weak :(

So can anyone tell me how to solve G?

UPD: now I know why I can't solve G.

Well, I now know why I couldn't solve G. I was stuck on calculating the maximal dissimilarity group and kept thinking about the following:

maintains a ds such that it supports the following operations:

• inserts an element
• deletes an element
• queries for the maximal value of the xor of each pair of elements in the set

But really, you just need to two pointer scan the array, and then deal with the contribution to the answer from the element currently pointed to by the right pointer, which is a classic 01-Trie problem. Regardless, the quality of the questions in this game was very high and I love it very much!

Is O(N * M * M) solution feasible in problem F ?? This is equivalent to 1e8 operations. One of the codes passed the TCs but I doubt about strength of TCs.

Good quality problems. I made so many stupid mistakes lol and so I didn't get time for G, but I knew immediately that we can just use a trie to get the max XOR, then iterate over l and find the nearest r such that a[l]^a[r] = max_xor.

I do have one contention though -- tries in div 3 problems. It's not that tries are too difficult for div 3, but rather there are much better alternatives, like some graph problem or something. This is probably the third time I've seen a trie in div 3.

D was very wrong placed , i spend my entire time on d why there are lots of ac in d ??

Why my 314649703 for E — Min Max MEX TLE?

I wonder, don’t you have any testers to tell you that this contest is bad? I’d like to know what you were thinking when you included problems C and D. Problem E was much easier, except for the text of problem F. Are we here so you can test our ability to read English?

This contest was a waste of time.

When I’m not good at something, I leave it to someone else.

4 5
a s k A
d s D t
O R i A
a X b Y
b a k A
u s k J  
why is answer to this 8 not 10

wtf was D bro I wasted 1.5hrs on it. I should have solved E before it was simple binary search

I feel like my solution for E is hackable because I used sets instead of arrays to track which elements have been filled so far. More than 1000ms in C++ is not good news...

Link to my submission

Hacks appreciated

E was easier than B

It was more of a div4 than a div3.

Why the authors in recent div3's have removed the notes section from problem statement $$$?$$$ In today's contest, there were no notes except for task $$$D$$$.

What is the corner case in G? I'm creating a trie of all seen numbers and searching as follows:

if k has this bit 0 and we can make this bit 1, then simply return the max index of any number seen so far that does so, otherwise continue down the tree.

if k has bit 1, make sure to take the branch which makes this bit 1, if there is no such branch, then return -1. If we reach end of the tree then return the max idx as we must have atleast matched the value of k.

I read this probelm is very intersting but i found some cheater in this contest. How can report them?

In problem c, is there exist any prime number greater than 1000? someone pls help...:(

Problem D is litteraly to toxic to put in a D div 3 i think even G is more straight forward and easier than D (although i didn't solve G cause i ran out of time)

Why the problems dont have notes to explain the example test

nice Codeforces round!!!

Was problem $$$G$$$ solvable using Trie and two-pointers ?

Today's G was so similar to this problem: https://oj.uz/problem/view/IZhO12_xor

Here is my screencast of this contest along with the solution ideas and thought process: https://youtu.be/6suW6LZyYtY

I am planning to do more of these videos if my schedule allows it.

Lol this absolute bruteforce passed for C

def readList():
    return list(map(int, input().split()))
def readInt():
    return int(input())
def readInts():
    return map(int, input().split())
def readStr():
    return input().strip()
def print_array(arr):
    print(" ".join(map(str, arr)))
def printer(is_True):
    print('YES') if is_True else print('NO')
def random_seed():
    return random.randint(0,10**9+7)
def is_prime(n):
    """returns True if n is prime else False (https://github.com/cheran-senthil/PyRival/blob/master/pyrival/algebra/is_prime.py)"""
    if n < 5 or n & 1 == 0 or n % 3 == 0:
        return 2 <= n <= 3
    s = ((n - 1) & (1 - n)).bit_length() - 1
    d = n >> s
    for a in [2, 325, 9375, 28178, 450775, 9780504, 1795265022]:
        p = pow(a, d, n)
        if p == 1 or p == n - 1 or a % n == 0:
            continue
        for _ in range(s):
            p = (p * p) % n
            if p == n - 1:
                break
        else:
            return False
    return True
for _ in range(readInt()):
    x,k=readInts()
    n=int(str(x)*k)
    printer(is_prime(n))

what is the possibility that using unordered_map in E causes hack?

We have numerous "unexpected verdict" E hacks, which usually indicates std also fails lmao