Enhance sentinel_linear_search doctests with comprehensive examples by JesunAhmadUshno · Pull Request #14284 · TheAlgorithms/Python

JesunAhmadUshno · 2026-02-17T10:45:17Z

Summary

Enhanced doctest coverage for sentinel_linear_search() with 15 comprehensive test examples covering:

Valid searches (first, middle, last element)
Invalid searches (element not found)
Edge cases (empty list, single-element list)
Type variations (integers, strings, floats, negative numbers)
Duplicates (finding first occurrence of duplicated values)

Changes

Added 11 new doctest examples (from 4 → 15 total)
Improved docstring documentation explaining the algorithm's sentinel approach
All tests pass locally: python -m doctest -v sentinel_linear_search.py

Checklist

I have read the CONTRIBUTING.md file
This is my own work and not plagiarized
My work will be distributed under the MIT License once merged
My submission follows the coding style and standards of this repository
I have tested my changes locally
All doctest examples pass
Code passes ruff linting

Copilot

Pull request overview

This PR primarily aims to enhance documentation and doctest coverage, but it also includes several unrelated typing refactors and small cleanups across the repository.

Changes:

Expanded sentinel_linear_search() docstring and doctest examples (4 → 15).
Refactored type parameter declarations in jump_search() and valid_input() to use modern generic syntax.
Broadened bipartite-check graph typing to accept generic hashable nodes and updated handling for neighbor-only nodes.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
searches/sentinel_linear_search.py	Adds a more detailed algorithm explanation and many more doctest examples.
searches/jump_search.py	Updates generic typing style and removes unused typing imports.
machine_learning/linear_discriminant_analysis.py	Updates `valid_input` generic typing and removes `TypeVar`.
graphs/check_bipatrite.py	Generalizes graph node types and changes semantics for neighbor-only nodes; removes FIXME doctest comments.
data_structures/hashing/hash_table_with_linked_list.py	Minor cleanup: uses `deque()` instead of `deque([])`.

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Copilot · 2026-02-17T10:51:02Z

searches/jump_search.py

+def jump_search[T: Comparable](arr: Sequence[T], item: T) -> int:
    """


The PR title/description focuses on doctests for sentinel_linear_search(), but this change set also modifies typing/generics in other modules (e.g., jump_search, LDA valid_input, bipartite checks, hash table). Please update the PR description to reflect these changes or split them into separate PRs so review/rollback scope is clear.

@copilot open a new pull request to apply changes based on this feedback

Copilot · 2026-02-17T10:51:02Z

graphs/check_bipatrite.py

    >>> is_bipartite_dfs({0: [1, 3], 1: [0, 2], 2: [1, 3], 3: [0, 2], 4: [0]})
    False
    >>> is_bipartite_dfs({7: [1, 3], 1: [0, 2], 2: [1, 3], 3: [0, 2], 4: [0]})
    False

-    >>> # FIXME: This test should fails with KeyError: 4.
    >>> is_bipartite_dfs({0: [1, 3], 1: [0, 2], 2: [1, 3], 3: [0, 2], 9: [0]})
    False


With the new behavior that neighbor nodes missing from graph are treated as having no outgoing edges, the example is_bipartite_dfs({7: ..., 4: [0]}) appears bipartite under the docstring definition, but the current algorithm returns False because it starts node 4 with an arbitrary color that can conflict with already-colored neighbor-only nodes. Consider choosing the start color based on any already-visited neighbors (or otherwise reconciling components), and update the doctest expected value accordingly.

@copilot open a new pull request to apply changes based on this feedback

Copilot · 2026-02-17T10:51:03Z

graphs/check_bipatrite.py

    False
    >>> is_bipartite_bfs({7: [1, 3], 1: [0, 2], 2: [1, 3], 3: [0, 2], 4: [0]})
    False

-    >>> # FIXME: This test should fails with KeyError: 4.
    >>> is_bipartite_bfs({0: [1, 3], 1: [0, 2], 2: [1, 3], 3: [0, 2], 9: [0]})
    False


Same issue as DFS: for graphs where some nodes appear only as neighbors (not keys), starting a new BFS component with color 0 can create a false conflict against an already-colored neighbor-only node (e.g., the {7: ..., 4: [0]} example). Initialize the component’s start color based on any already-colored neighbors (and verify consistency), or adjust the doctest/contract so the function’s behavior matches the documented bipartite definition.

@copilot open a new pull request to apply changes based on this feedback

Copilot · 2026-02-17T10:51:03Z

searches/sentinel_linear_search.py

@@ -18,6 +18,11 @@ def sentinel_linear_search(sequence, target):
    :param target: item value to search
    :return: index of found item or None if item is not found

+    The sentinel linear search algorithm works by appending the target value to the
+    end of the list before searching. This eliminates the need for boundary checking
+    during the loop, as the search is guaranteed to find the target (at minimum, at
+    the end where the sentinel is placed).


The docstring describes sequence as “some sequence”, but the implementation requires a mutable list-like object because it calls append() and pop() and mutates the input (even if it restores it). Please clarify the accepted type (e.g., list/MutableSequence) and explicitly note the temporary mutation, or change the implementation to avoid mutating the caller’s object.

@copilot open a new pull request to apply changes based on this feedback

…ations

Fix typing and lint issues

dda99e6

Copilot AI review requested due to automatic review settings February 17, 2026 10:45

Copilot started reviewing on behalf of JesunAhmadUshno February 17, 2026 10:45 View session

algorithms-keeper bot added the tests are failing Do not merge until tests pass label Feb 17, 2026

Copilot AI reviewed Feb 17, 2026

View reviewed changes

Enhance sentinel_linear_search doctests with edge cases and type vari…

c8d6bab

…ations

JesunAhmadUshno force-pushed the enhance-sentinel-search-doctests branch from a2dd3c3 to c8d6bab Compare February 17, 2026 10:53

algorithms-keeper bot removed the tests are failing Do not merge until tests pass label Feb 17, 2026

algorithms-keeper bot mentioned this pull request Feb 17, 2026

Enhance linear_search and rec_linear_search with comprehensive doctests #14287

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		def jump_search[T: Comparable](arr: Sequence[T], item: T) -> int:
		"""

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JesunAhmadUshno commented Feb 17, 2026

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