const grid = [ collect(line) for line in readlines("input/8") ]
const size = length(grid)

const Coords = Tuple{Int,Int}

ants::Dict{Char,Vector{Coords}} = Dict()
for (y,row) in enumerate(grid)
	for (x,c) in enumerate(row)
		if c != '.'
			get!(ants, c, []) .= push!(ants[c], (x, y))
		end
	end
end

isOnMap(n) = 1 <= n[1] <= size && 1 <= n[2] <= size
partOneGrid = deepcopy(grid)

partOneSet, partTwoSet = Set(), Set()

for (freq,coords) in ants
	for (a,b) in Iterators.filter((x) -> x[1] != x[2], ( sort([a, b]) for a in coords, b in coords ))
		local diff = a .- b
		for n in (a .+ diff, b .- diff)
			if isOnMap(n)
				push!(partOneSet, n)
			end
		end
		for (n,fn) in ((a,.-), (b,.+))
			while isOnMap(n)
				n = fn(n, diff)
				if isOnMap(n)
					push!(partTwoSet, n)
				end
			end
		end
	end
end

const partOne, partTwo = length(partOneSet), length(partTwoSet)

@show partOne, partTwo