[Fix #109] Added Solution for Easy Difference Array Problem (CSES 1651)

[Krishna200608]

Issue : #109

Summary

This PR adds the C++ solution for the "Easy" problem listed in the Difference Array readme: CSES 1651 - Range Update Queries.

Submission Proof

Link : https://cses.fi/paste/e46fc0236a874a04f11078/

Screenshot

Changes Made

• Solution1.cpp: Implemented the solution using a Fenwick Tree (BIT) backed by the Difference Array concept.
• Reasoning: While standard difference arrays are static, this problem requires online updates and queries. The implementation achieves O(log N) per operation instead of O(N), ensuring it passes within time limits.

Complexity

• Time: O((N + Q) log N)
• Space: O(N)

Checklist

• Code compiles and passes test cases.
• Followed directory structure algos/range_queries/DifferenceArray/soln/.
• Added comments explaining the approach.

[OpenGitBot]

Hey @Krishna200608

PR Template is not followed. Kindly follow the template & edit it again for consideration as a valid pull request.

Thanks for contributing in OpenCode'25 ✨✨!

Correct Tempelate:
Issue : #<Issue_Number>

[OpenGitBot]

Hey @Krishna200608

PR Template is not followed. Kindly follow the template & edit it again for consideration as a valid pull request.

Thanks for contributing in OpenCode'25 ✨✨!

Correct Tempelate:
Issue : #<Issue_Number>

[OpenGitBot]

Hey @Krishna200608

Thanks for opening this PR 🚀. Mentor will review your pull request soon and till then, keep contributing and stay calm.

Thanks for contributing in OpenCode'25 ✨✨!