* Add cpplint to validate_filenames

* Update and rename Happy_number.cpp to happy_number.cpp

* Update validate_new_filenames.yml

* pip install cpplint

* python3 -m pip install cpplint

* python3 -m pip install --useer cpplint

* python3 -m pip install --user cpplint

* Update validate_new_filenames.yml

* sudo python3 -m pip install cpplint

* sudo python3 -m pip install cpplint

* uses: actions/setup-python@v1

* Run cpplint first

* cpp_exts

* tuple

* cpplint_modified_files

bugfix Update and rename knight-tour.cpp to knight_tour.cpp

Add information about the file for brief intro

Rename N Queens.cpp to n_queens.cpp

GitHub Action to run cpplint on all pull requests

Just like #640 but:
1. Does a git diff and only checks newly added .cpp files
2. Embeds the Python code directly in the .yml file

feat: add Kosaraju's algorithm to find all the strongly connected components in a graph. 

Change file name.

Updated with proper function definitions
Information about method included
@param parameter : what it is/explanation included
@return return type included

median search

Added FenwickTree For Range Query

function definitions - what it does with its type (iterative/recursive) 
common terms/annotations
2 statements marked as debug, removed other comments (as I kept them while coding)
added comments to main function

Add Pascal's Triangle Algorithm

change file name and put code inside a function

I modified a link(Contribution guidelines)

Revert "Created PigeonHole sorting algorithm"

Created PigeonHole sorting algorithm

The 'contribution guidelines' link is incorrectly linked, so I fixed it with the correct link.

Feat: Add/Format Readme.md Contribution.md and pull-request-template.md