How to achieve this multidimensional array in the most efficient way?

I wouldn't make it an array, but rather an object ... since you are using it like an object anyways. (If you aren't using integer indexes and the length property, you using the array like a basic object anyways. All arrays are objects, not all objects are arrays.).

This would give you an object with dynamic properties.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.