Refactor Segment Tree Implementation

[sozelfist]

Checklist:

• [x] I ran bellow commands using the latest version of rust nightly.
• [x] I ran cargo clippy --all -- -D warnings just before my last commit and fixed any issue that was found.
• [x] I ran cargo fmt just before my last commit.
• [x] I ran cargo test just before my last commit and all tests passed.
• [x] I added my algorithm to the corresponding mod.rs file within its own folder, and in any parent folder(s).
• [x] I added my algorithm to DIRECTORY.md with the correct link.
• [x] I checked COUNTRIBUTING.md and my code follows its guidelines.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 95.43%. Comparing base (3422002) to head (46b3405). Report is 2 commits behind head on master.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #835 +/- ## ========================================== + Coverage 95.42% 95.43% +0.01% ========================================== Files 315 315 Lines 22806 22809 +3 ========================================== + Hits 21762 21768 +6 + Misses 1044 1041 -3 ```

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[sozelfist]

Can you have a look, @vil02?