#7209 Add Prefix Sum based solution for Range Sum Query

[saignaeshdasari]

….java and prefixsum1.java

• Added Java implementation using Prefix Sum technique
• Improves time complexity for multiple range queries
• Follows repository contribution guidelines

• 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 algorithms include a corresponding test class that validates their functionality.
• All new code is formatted with clang-format -i --style=file path/to/your/file.java

[codecov-commenter]

Codecov Report

❌ Patch coverage is 0% with 30 lines in your changes missing coverage. Please review.
✅ Project coverage is 78.93%. Comparing base (66f76eb) to head (72cea60).

Files with missing lines	Patch %	Lines
...in/java/com/thealgorithms/prefixsum/prefixsum.java	0.00%	16 Missing ⚠️
...n/java/com/thealgorithms/prefixsum/prefixsum1.java	0.00%	14 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #7210      +/-   ##
============================================
- Coverage     79.05%   78.93%   -0.13%     
+ Complexity     6941     6940       -1     
============================================
  Files           778      780       +2     
  Lines         22898    22928      +30     
  Branches       4501     4505       +4     
============================================
- Hits          18103    18099       -4     
- Misses         4076     4108      +32     
- Partials        719      721       +2     

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