Day 17

Feelings

Well.. Part 2 ended up being a complete copy-paste of part 1, but with adding one more dimension. Should generalise neighbor searches somehow.

Learnings

Learned itertools.multi_cartesian_product
And implemented my very first actually useful macro (see below)
- Maybe I'll be able to convert this to generic type instead some day, but that day is not today

.. later same day

pub trait VecNeighbors<T> {
    fn neighbors(&self) -> Vec<Vec<T>>;
}

macro_rules! VecNeighbor_for {
    ($vectype:ty) => {
        impl VecNeighbors<$vectype> for Vec<$vectype> {
            fn neighbors(&self) -> Vec<Vec<$vectype>> {
                self
                    .iter()
                    .map(|v|(v-1 ..= v+1).into_iter())
                    .multi_cartesian_product()
                    .filter(|x| x != self)
                    .collect::<Vec<_>>()
            }
        }
    };
}

Implement it:

    VecNeighbor_for!(i32);

.. and then just use it:

    fn test_vecneighbor() {

        let _coord:Vec<i32> = vec![0,0];
        for x in _coord.neighbors().into_iter() {
            println!("{:?}", &x);
        }
    }

Which gives you this:

[-1, -1]
[-1, 0]
[-1, 1]
[0, -1]
[0, 1]
[1, -1]
[1, 0]
[1, 1]