Codeforces - ddos attack

Codeforces page is showing " Sorry it is a DDOS attack "?
What does it mean ?


Distributed Denial of Service… It is well explained in this video


Hope you didn’t use your bank password here, or say good bye to your money.

Ohhhhhhhhhhhhhhhhh okaaaay

I don’t think anyone can steal your password from ddos.

Dummies click here

ddos is not stealing passwords from database . its is a denial attack on the website which cause huge traffic and crash servers .for learning check this video from computerphile

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Hi , could you solve D?

Password cannot be stolen using DDos

I was getting wrong at pretest 9 for problem C could anyone explain his approach ??

binary search for the value of minimum days. Though the code is self explanatory still if you have any doubts you can ask.
this code passed the pretests (not sure about systests)

Binary search on length . Put maximum on lcm(a,b) positions and then on multiples of a and b respectively. How did you solve?

what was your solution binary search??

I used the same approach didn’t know why i was getting wrong answer

Did anyone solve D , any ideas? that was my one of submission !!!

To calculate the number of subarrays that makes the stack empty you have to just find the first R for each L that L - R makes the stack empty then it’s a basic dp.

For a naive solution use a jump array and keep jumping in O(N), so N ^ 2 in total. Optimize by using DSU to keep the possible starting indices we can jump to and their values.

Complexity is O(NlogN)