fix: Nearest Greater and Smaller Element Algorithm (Fixes #6656)

[sgindeed]

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• This pull request is all my own work -- I have not plagiarized it.
• All filenames are in PascalCase.
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[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 75.87%. Comparing base (3eb521b) to head (52c4f7a).

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #6693      +/-   ##
============================================
+ Coverage     75.80%   75.87%   +0.06%     
- Complexity     5804     5828      +24     
============================================
  Files           705      706       +1     
  Lines         19846    19890      +44     
  Branches       3851     3863      +12     
============================================
+ Hits          15045    15091      +46     
+ Misses         4218     4217       -1     
+ Partials        583      582       -1     

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