Complex Numbers: Add benchmarks

[andrerfcsantos]

On one of my recent mentoring sessions, I noticed the exercise complex-numbers doesn't have any benchmarks.

Benchmarks are not as critical in this exercise as it is in others, but some functions can be optimized, and would be nice to have benchmarks to show students what those improvements can mean performance-wise.

Contributing to this issue

Anyone is welcome to contribute to this issue. If you are interested in working on this, just post a comment below saying you want to work on this.

This issue requires you to write one or more benchmark functions. Ideally each function the student is required to write for the exercise should have a corresponding benchmark function.

Here are some links to help you on this task:

• How to write benchmarks in Go
• Example of benchmark function for the "Allergies" exercise
  • Several other exercises also contain benchmarks. You can see those by looking up Benchmark* functions in *_test.go files for more examples.

[W8CYE]

@andrerfcsantos I'll take this one.

[andrerfcsantos]

@W8CYE All yours. Thanks for the interest in tackling this 👍