[OS] implement semaphore binary & counter

[OS] implement the logic of locks

[OS] slides of UMASS OS 377

[OS] process management

add course slides

useful books

first 2 videos in database cmu course

OS first 3 videos in CS 377

fix chaining implementation link

fix link in readme file

Hash tables

linked lists

Array based Stack & Queue

refactor testinf file and process

edit Array flow structure