Palindrome singly linkedlist optimised approach

[Nandini-Pandey]

• 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.
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[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 58.08%. Comparing base (4a5bf39) to head (b7c9c23).

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #5617      +/-   ##
============================================
+ Coverage     58.01%   58.08%   +0.07%     
- Complexity     3660     3669       +9     
============================================
  Files           546      546              
  Lines         15749    15776      +27     
  Branches       2996     3000       +4     
============================================
+ Hits           9137     9164      +27     
  Misses         6224     6224              
  Partials        388      388              

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