Match3 algorithm

Hi there. My first post.
I’m working on match3-like project rigth now. I had the basic concept of a game. You have a grid. You uave donats of different colors stacked on each other. You control randomly generated stack of donuts by dragging it between rows of a grid and when you release touch the stuck falls al the way down like in tetris. If stack contains zero donuts or all three donuts of same one color it disappears from the board.
The main goal was to implement an algorithm which wisely rearrange the donuts to achive the maximum effectiveness. I’ve created project, core architecture, prefabs, basic logic and started to implement algorithm itself. The idea was to store every stuck on the board as List of structs that contains stack itself and Vector2 position in matrix to have the ability to find every elements neighbors. Algorithm should get the new stack, check for it’s neighbors, exchange donuts and run itself for each neighbor or return if none donuts were exchanged.
But now I end up with 100+ lines of code function that sometimes works in very unexpected ways. I can show the whole algorithm here if needed but what I really need is an idea how to make it smart and simple.
Another my idea was in storing everything in same list but instead of recursive calling function on neighbors use while loop and mark modified elements with some bool and run function on that elements until all become unmarked. That’s not a big difference tho.
So if you have good ideas on how to implement such an algorithm, I will be very happy to hear them.

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