How does the Litecoin difficulty get calculated? Bitcoin creates 2016 blocks, and if the average time of 2016 blocks is less than 10 minutes, the difficulty increases. If it is more than 10 minutes, the difficulty decreases.

How does the Litecoin mining difficulty get adjusted?
Litecoin is a fork of Bitcoin Core, and uses the same difficulty adjustment period (2016 blocks), which on Litecoin is 3.5 days because the block time is 2.5 minutes instead of 10.  See chainparams.cppL#85:

consensus.nPowTargetTimespan = 3.5 * 24 * 60 * 60; // 3.5 days
consensus.nPowTargetSpacing = 2.5 * 60;