fix bugs, add descriptions, and add tests (keon#486)

* refactor(pylint): unionfind/count_islands.py

improves pylint score from 3.71 to 10.00

fixes KTH-Software-Engineering-DD2480#2

* refactor(pylint): algorithms/search/*.py

improves pylint score from 5.83 to 10.00.

fixes KTH-Software-Engineering-DD2480#7

* feat: improving pylint score

* refactor dp.combination_sum: lint score from 5.42 to 9.13

* refactor(pylint): algorithms/graph/*.py

Improves pylint score from 5.51 to 9.96.

Score is lower than 10 due to duplication between maximum_flow_bfs.py
and maximum_flow_dfs.py. However, due to the educational nature of this
repo, keeping it as is will probably be benefitial as it reduces
complexity while reading (having to jump between files).

fixes KTH-Software-Engineering-DD2480#9

* refactor egg_drop, hosoya_triangle, min_cost_path and planting_trees

* feat: improving pylint score of one_sparse_recovery

* refactor: move tests from regex_matching to tests folder

* refactor: lint score from 4.27 to 9.46

a reason that lint score isn't 10.00 is that the module is called dp,
which in turn makes pylint raise invalid name for all files in dp.
I leave that as it is, since I don't want to mess with the current folder structure.

fixes #3

* Fix: Fixed lint error, lint value now aboe 8

* refactor: add docstring to misra, score 10

* fix (misra): add a newline

* refactor: add docstring for one_sparse, score 9.33

* wip: refactor (pylint): algorithms/maths/
wip: #4

* Fix: pylint is above 8 for tree

* refactor (pylint): algorithms/maths/
Finished improving pylint score for maths folder.
fixes: #4

* Fixed: comments

* fix: small intendation fix

Co-authored-by: ekorre1001 <skyever@hotmail.se>
Co-authored-by: Philip Salqvist <philipsalqvist@MacBook-Pro-som-tillhor-Philip.local>
Co-authored-by: psalqvist <63300368+psalqvist@users.noreply.github.com>
Co-authored-by: Kubha99 <1kunalbhatnagar@gmail.com>
Co-authored-by: mantaur <mark.spel.konto@live.se>