MEV builder algorithms

Hi all,

I am looking for a source that explains the algorithm on how the block builders select the transactions from the mempool. The only thing that looks close is this code from flashbots

https://github.com/flashbots/builder/blob/45e865eb2fc20f03f193fc1365e7dc2622c61ced/miner/worker.go

however it is still hard for me to parse and understand the algorithm. I haven't found anything else from the other builders. I guess the algorithms from the others are private?

Any thoughts/suggestions?