go.wperron.io/fizzbuzz-codegen

FizzBuzz in O(1) Using Codegen

Why you may ask? Well... I was bored, that's why 🤷‍♂️

How does it work?

In the traditional FizzBuzz problem, using the factors 3 and 5, we can notice an infinite sequence when printing the whole sequence of numbers. That sequence has a length of 15, which happens to be the product of all the factors that we want to include in our algorithm.

1, 2, Fizz, 4, Buzz, Fizz, 7, 8, Fizz, Buzz, 11, Fizz, 13, 14, FizzBuzz

This works for 3 and 5, but it also works for any pair of numbers, and even also works for any set of numbers.

For example, given the set [a, b, ..., n] we can determine that the repeating sequence of our FizzBuzz game will have a length of a x b x ... x n. We can also write an algorithm that is going to sieve through all of our factors in this set and generate the sequence for us, with the right word substituted in the right place.

From there, all we have to do is take our input number, take its modulo against the length of the sequence, and we have the index in the sequence where the answer will be. If that index returns an empty string, then we simply return the input number back.

How to use this thing?

The code generator is located in codegen/main.go and takes to named parameters:

• -o - File path where the generated code will be written to.
• -p - Package name for the generated file. Defaults to main.

The factors to use are positional arguments, they should be alternated with the word to be used in the substitution.

complete example:

$ go run ./codegen -o lib.go -p main 3 Fizz 5 Buzz

Go Generate

The entrypoint main.go already contains a //go:generate comment so simply running go generate will also work.