How to classify a 3D "Knapsack" problem where the only limitation is space, i.e. there is no weight constraint?
In the standard Knapsack problem (solvable by DP) when we are packing objects we do not care about how we put objects in the knapsack, i.e., what only matters is a subset of objects and the sum of weights of these objects. But, in cuboid/rectangle packing problem the configuration of the cubes/rectangle is important to achieve the optimal packing. So, from this point of view these problems are different. I googled and found this heuristic approach and this article.