https://www.youtube.com/playlist?list=PLBqHLq3IFiRKS3KBFUGwHmG7Utj5z5pBS
Easily learn concepts of STL . This channel also has various other cool stuff and the best part is you can request stuff in the comments and you get that video the same day or next at max .
You also have all the editorials and android app development courses . Please do subscribe and give suggestions .