julia start

julia/PolyCube.jl

@@ -0,0 +1,53 @@
+include("tuple_tools.jl")
+
+import Combinatorics: powerset
+
+Coord = Tuple{Number, Number, Number}
+
+struct PolyCube
+    cubes::Vector{Coord}
+    oriented_difference::Vector{Vector{Coord}}
+    last_added::Vector{Coord}
+end
+
+function PolyCube(cubes::Vector{Coord}, last_added::Vector{Coord})
+    return PolyCube(sort!(cubes), _calculate_oriented_differences(cubes), last_added)
+end
+
+# possible improvement: since reorientation[1] == cubes, skip the insertion sterp, and benefit from having cubes sorted.
+# then skip sorting in constructor
+
+function _calculate_oriented_differences(cubes::Vector{Coord})
+    n_orientations = 24
+    n_cubes = length(cubes)
+    reorientation = Vector{Coord}(undef, n_cubes)
+    oriented_differences = Vector{Vector{Coord}}(undef, n_orientations)
+    for i ∈ 1:n_orientations
+        for j ∈ 1:n_cubes
+            reorientation[j] = orient_tuple(cubes[j], i)
+        end
+        sort!(reorientation)
+        reference_cube = reorientation[1]
+        oriented_differences[i] = Vector{Coord}(undef, n_cubes-1)
+        for j ∈ 1:n_cubes-1
+            oriented_differences[j] = reference_cube - reorientation[j+1]
+        end
+    end
+    return oriented_differences
+end
+
+function generate_children(pcube::PolyCube, n_max::Int)
+    cubes = pcube.cubes
+    allowed_growth = n_max - length(cubes)
+    growth_candidates = Vector{Coord}(undef, 0)
+    for root_cube ∈ pcube.last_added
+        for neighbor ∈ neighbors(root_cube...)
+            pos_growth_candidates = searchsortedfirst(growth_candidates, neighbor)
+            # consider flipping following ||, it MAY imrove performance
+            if growth_candidates[pos_growth_candidates] != neighbor || !isempty(searchsorted(cubes, neighbor))
+                insert!(growth_candidates, pos_growth_candidates, neighbor)
+            end
+        end
+    end
+    return Iterators.map(x -> PolyCube(vcat(cubes, x), x), powerset(growth_candidates, 1, allowed_growth))
+end