Add word ladder algorithm in backtracking (#11590)

* Add word ladder algorithm in backtracking

* Improve comments and implement ruff checks

* updating DIRECTORY.md

* [pre-commit.ci] auto fixes from pre-commit.com hooks

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* Change BFS to Backtracking

* [pre-commit.ci] auto fixes from pre-commit.com hooks

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* Incorporate PR Changes

* [pre-commit.ci] auto fixes from pre-commit.com hooks

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* Add type hints for backtrack function

* [pre-commit.ci] auto fixes from pre-commit.com hooks

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Co-authored-by: Hardvan <Hardvan@users.noreply.github.com>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>