refactor: Enhance docs, add more tests in ArrayCombination

[Hardvan]

• I have read CONTRIBUTING.md.
• This pull request is all my own work -- I have not plagiarized it.
• All filenames are in PascalCase.
• All functions and variable names follow Java naming conventions.
• All new algorithms have a URL in their comments that points to Wikipedia or other similar explanations.
• All new code is formatted with clang-format -i --style=file path/to/your/file.java

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 66.03%. Comparing base (adf21ab) to head (75e31a1).

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #5841      +/-   ##
============================================
- Coverage     66.04%   66.03%   -0.02%     
+ Complexity     4409     4408       -1     
============================================
  Files           605      605              
  Lines         16827    16827              
  Branches       3232     3232              
============================================
- Hits          11114    11112       -2     
- Misses         5266     5267       +1     
- Partials        447      448       +1     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.