Do some research about data structures :)

They are two parameters of a lambda expression

What are "r" and "i"? they are not declared...

Thanks! My shortURL generator is not based on randomness, but still I can't achieve not to iterate every time on the DB... I can run 35.764 tests before getting out of time...

You don't need a complicated algorithm to solve this kata, but iterating each time through the whole database to check if a URL was used before or generating short URLs based on randomness, won't pass.

Hey guys! I'm having some trouble to solve this kata, I passed the first test, but when I attemp, I'm having this message error:
"Execution Timed Out (16000 ms)"
I guess that I have a performance problem, am I right? Do you have any clue to help me pass this kata?

This is some beautiful code!

as the user 'miyatanimi' discussed with 'B1ts' a few days ago: "you are not allowed to match multiple values of one array to one value of the second array.

I have no clue what this could mean...
edit: I discovered it :)))))

I had a filter to return false, if passed arrays are null or empty. My mistake was to assume that arrays cant be empty

Print the input.

I can´t pass test10, does anyone knows the given parameters of that test?