Implement Trapped Rain Water Problem

[sozelfist]

Type of change

• [x] New feature (non-breaking change which adds functionality)

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 94.78%. Comparing base (b86b003) to head (c2f9c3a).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #712 +/- ## ======================================= Coverage 94.78% 94.78% ======================================= Files 299 300 +1 Lines 22245 22274 +29 ======================================= + Hits 21084 21113 +29 Misses 1161 1161 ```

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