Hashset Implementation w chaining from scratch no built in libraries

Implemented stack data structure in python

Backtracking guide, template, and exercises

Update linkedlist.py

slight update to methods functionality

linked list implementation with all basic operations working and tested

Revert "linked list implementation with all basic operations working and testing; leetcode question 206 submission"

linked list implementation with all basic operations working and testing; leetcode question 206 submission

Initial commit