What is the convention for organising interfaces and their implementations in a Go project?

What is the convention for organising interfaces and their implementations in a Go project?

I am new to Go and creating a small project, I currently have this folder structure:

src/
    my-repo/
        solve/
            backtracksolve.go
            permutatesolve.go
            ...
            solver.go

... (some repositories and packages omitted for brevity) ...

backtracksolve and permutatesolve both implement the interface solver so it make sense to keep them in the same package as the interface and other implementations of that interface, coming from Java/C# this is a common convention for example, java.util contains interfaces such as Set, Map, List, while also having implementations such as HashSet, HashMap and ArrayList.

However in Go because they both implement a func Solve() and both in the package solve there is redeclared exception.

Is it the convention to create a sub directory for each implementation (below) or something completely different?

src/
    my-repo/
        solve/
            backtrack/
                backtracksolve.go
            permutation/
                permutatesolve.go

            solver.go