What are the rules for building 3-in-a-row puzzles?

Question

Unity

Take for example a puzzle of type 3 in a row, that is, for example, there is a rectangular board on which there are balls of different colors, moving them up / down or left / right if 3 or more identical colors in a row match (horizontally or vertically) they disappear, then all the rest fall in their place, empty ones fill new ones.

The question is how to line them up correctly and, after destruction, build new ones so that there are still opportunities for movement, so that there is no such thing as removing colors and after adding new ones there simply were no moves?

I think this should somehow be calculated, that's just how, tell me articles on a similar topic, or how to build this business correctly.

Answer 1

As an option, before displaying, generate the balls that will fall in the places of the remote ones. Then check for the presence of combinations, if there are none, then repeat this procedure.