While it's a correct approach, it's not the most efficient due to the repeated string manipulation and the use of deprecated characters property.

Clever! but can cause performance hit and also not works in reality where something other than Braces involves.

I agree with antong01. This problem is best solved in O(n) by not sorting either array, but instead making use of a dictionary. Most of the solutions submitted either use sorting which results in O(n log n) or searching through an array, which results in O(n^2) overall. While simple and concise to write, they don't scale as well.

While this is a simple solution, it has complexity of O(n log n); For big arrays it could be suboptimal if the first first element of a didn't have a match (no early return) or if b was an empty array

great solution :) takes some time to complete though.

@Renaissance8905: I use guard any time I can to escape early. In this case, the return arr is an early escape in case times equals zero. So I don't only use guard in failure cases, but edge cases in general.

The added benefit here is that we don't have to scan the guard body for a return statement, since the compiler enforces it.

Thanks! I'm curious, what's your criteria for using guard vs. if? I typically only use guard when failing the guard would be interpreted as a failure case for the method, or when I'm trying to unwrap an optional that I'd need to use later in the method.

Nice! I like this solution a lot, but I'd use guard rather than if :)