Implemented doctests for geometry-related classes (#12368)

* Implemented doctests for geometry-related classes

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

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* Removed unused noqa directive

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

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* refactored sudoku_solver.py

* refactored sudoku_solver.py

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* context manager for file handling changed too in from_file function

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Tianyi Zheng <tianyizheng02@gmail.com>

data_structures/arrays/sudoku_solver.py

@@ -23,7 +23,7 @@ unitlist = (
     + [cross(rs, cs) for rs in ("ABC", "DEF", "GHI") for cs in ("123", "456", "789")]
 )
 units = {s: [u for u in unitlist if s in u] for s in squares}
-peers = {s: set(sum(units[s], [])) - {s} for s in squares}  # noqa: RUF017
+peers = {s: {x for u in units[s] for x in u} - {s} for s in squares}
 
 
 def test():
@@ -172,7 +172,8 @@ def solved(values):
 
 def from_file(filename, sep="\n"):
     "Parse a file into a list of strings, separated by sep."
-    return open(filename).read().strip().split(sep)
+    with open(filename) as file:
+        return file.read().strip().split(sep)
 
 
 def random_puzzle(assignments=17):