Because there's no need to create another copy of str.

string str : is a fixed, read-only string stored in memory. You cannot modify it. so it is more correct and safer to be (const) char[]

its better to reserve space for elements and emplace_back elements

go code by yourself, don't rely on Mathematics

...for what reason exactly?

Maths are much better for performance than just bruteforce.

Work smarter, not harder.

Great Solution!

how the hell this finish in time

one of the favoriate solution that I've seen

Brute-force solution, runs in O(n^2). Don't do this please, use a hash map instead which runs in O(n). Please, this is important for everyone.

I wouldnt worry about debuggability for total 4 lines of code

creative

huuuuuuuuuuuhh i still didnt learn pascal triangle (11G) and when i see solutions like this i feel like that i overthink stuff, what should i do?

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Bro, i felt so dumb after spent almost 10min trying to solve it lmao. But, at least, im learning something instead of playing something ;-;