Merge branch 'master' into fix-ty-invalid-assignment

Author: kadubhumika

.github/skills/code-review/SKILL.md

@@ -33,6 +33,24 @@ suggest the fix — never just "rejected".
 - [ ] Descriptive variable and function names (no single letters where a word helps).
 - [ ] Code is formatted and lint-clean (`ruff`, `pre-commit`).
 
+#### When a PR fails `ruff check`
+
+Don't just report the failure — try the mechanical fixes and recommend the one
+that works, in this order:
+
+1. Run `ruff check --fix file_path.py`. If that makes the file pass, recommend
+   that solution — these are the fixes `ruff` considers **safe**.
+2. If it still fails, run `ruff check --fix --unsafe-fixes file_path.py`. If that
+   makes the file pass **and** the resulting diff is genuinely safe (it preserves
+   behavior — review it, don't trust it blindly), recommend that solution and note
+   that it required `--unsafe-fixes`.
+3. If neither passes, or the unsafe fix would change behavior, describe the
+   remaining rule violations and the manual change the author needs to make.
+
+Always quote the exact rule code(s) `ruff` reports (e.g., `ruff rule UP047`,
+`ruff rule RUF100`) so the author can run those commands to read the rules being
+flagged. Also, paste the concrete command you ran.
+
 ### 3. Other Requirements for Submissions
 
 - [ ] At least one **Wikipedia (or equivalent) URL** documenting the algorithm.

.github/skills/new-pull-request/SKILL.md

@@ -0,0 +1,52 @@
+# Skill: New pull request for TheAlgorithms/Python
+
+Create a new pull request using the rules already written in
+[`CONTRIBUTING.md`](../../../CONTRIBUTING.md). The goal is that creating a new
+pull request (human or AI) can run the same way every time, and that produces a
+clear, kind, tested, type-hinted, mergeable contribution.
+
+## How to run this skill
+
+Make sure that the local `master` branch is synced with `upstream/master` before
+creating a new pull request.
+
+Create a new clearly named branch for the pull request.  Pull request changes must
+not be made or submitted on the `master` branch.
+
+Never hand-edit or revert the `uv.lock` file. If you add a legitimate
+dependency, let the `uv-lock` pre-commit hook regenerate it — do not touch it by
+hand. A hand-modified `uv.lock` makes the `algorithms-keeper` bot close the pull
+request as invalid, and even a repo maintainer cannot undo that.
+
+Always check at least one Markdown checkbox in the pull request description (the "Describe your change" section), or the
+`algorithms-keeper` bot will close the pull request as invalid.  Any repo maintainer can undo this if you @mention them on the closed pull request.
+
+### 1. Before contributing / Is this an algorithm?
+
+- [ ] The change adds, fixes, or documents **one algorithm** — not multiple, and
+      not both code and doctest changes in the same PR.
+- [ ] It is a genuine algorithm or data structure (see the *What is an Algorithm?*
+      section), not a script, snippet, how-to-use for an existing API, or exercise
+      dump.
+- [ ] It is **not already in the repository** (search the existing directories).
+- [ ] **No earlier open PR** already does the same thing — link it if one exists.
+- [ ] Properly attributed — no plagiarism; prior sources credited.
+
+### 2. Coding Style
+
+- [ ] `from __future__ import annotations` is not needed because this repo only uses
+      the latest version of CPython.
+- [ ] File and directory names are lowercase, use underscores, and land inside an
+      existing directory.
+- [ ] Public functions/classes have **type hints**.
+- [ ] Public functions have **doctests that actually pass**.
+- [ ] Descriptive variable and function names (no single letters where a word helps).
+- [ ] Code is formatted and lint-clean (`ruff`, `pre-commit`).
+- [ ] `DIRECTORY.md` and `README.md` are **not hand-edited** — the
+      `algorithms-keeper` bot regenerates them automatically after merge.
+
+### 3. Other Requirements for Submissions
+
+- [ ] At least one **Wikipedia (or equivalent) URL** documenting the algorithm.
+- [ ] Docstring explains what the function does and its parameters/returns.
+- [ ] No unnecessary third-party dependencies.

.pre-commit-config.yaml

@@ -29,13 +29,13 @@ repos:
           - tomli
 
   - repo: https://github.com/astral-sh/ruff-pre-commit
-    rev: v0.16.5
+    rev: v0.16.6
     hooks:
       - id: ruff-check
       - id: ruff-format
 
   - repo: https://github.com/tox-dev/pyproject-fmt
-    rev: v2.28.1
+    rev: v2.29.3
     hooks:
       - id: pyproject-fmt
 
@@ -48,7 +48,7 @@ repos:
         pass_filenames: false
 
   - repo: https://github.com/astral-sh/uv-pre-commit
-    rev: 0.12.7
+    rev: 0.12.10
     hooks:
       - id: uv-lock
 

DIRECTORY.md

@@ -696,8 +696,6 @@
   * [Support Vector Machines](machine_learning/support_vector_machines.py)
   * [T Stochastic Neighbour Embedding](machine_learning/t_stochastic_neighbour_embedding.py)
   * [Word Frequency Functions](machine_learning/word_frequency_functions.py)
-  * [Xgboost Classifier](machine_learning/xgboost_classifier.py)
-  * [Xgboost Regressor](machine_learning/xgboost_regressor.py)
 
 ## [Maths](maths)
   * [Abs](maths/abs.py)

README.md

@@ -17,9 +17,6 @@
   <a href="https://the-algorithms.com/discord">
     <img src="https://img.shields.io/discord/808045925556682782.svg?logo=discord&colorB=7289DA&style=flat-square" height="20" alt="Discord chat">
   </a>
-  <a href="https://gitter.im/TheAlgorithms/community">
-    <img src="https://img.shields.io/badge/Chat-Gitter-ff69b4.svg?label=Chat&logo=gitter&style=flat-square" height="20" alt="Gitter chat">
-  </a>
 
   <!-- Second row: -->
   <br>
@@ -45,7 +42,7 @@ Implementations are for learning purposes only. They may be less efficient than
 
 ## 🌐 Community Channels
 
-We are on [Discord](https://the-algorithms.com/discord) and [Gitter](https://gitter.im/TheAlgorithms/community)! Community channels are a great way for you to ask questions and get help. Please join us!
+We are on [Discord](https://the-algorithms.com/discord)! Community channels are a great way for you to ask questions and get help. Please join us!
 
 ## 📜 List of Algorithms
 

graphs/kahns_algorithm_topo.py

@@ -1,3 +1,6 @@
+from collections import deque
+
+
 def topological_sort(graph: dict[int, list[int]]) -> list[int] | None:
     """
     Perform topological sorting of a Directed Acyclic Graph (DAG)
@@ -21,10 +24,17 @@ def topological_sort(graph: dict[int, list[int]]) -> list[int] | None:
 
     >>> graph_with_cycle = {0: [1], 1: [2], 2: [0]}
     >>> topological_sort(graph_with_cycle)
+
+    >>> sparse_graph = {10: [20], 20: []}
+    >>> topological_sort(sparse_graph)
+    [10, 20]
+
+    >>> sparse_cycle = {10: [20], 20: [10]}
+    >>> topological_sort(sparse_cycle)
     """
 
-    indegree = [0] * len(graph)
-    queue = []
+    indegree = dict.fromkeys(graph, 0)
+    queue: deque[int] = deque()
     topo_order = []
     processed_vertices_count = 0
 
@@ -34,13 +44,13 @@ def topological_sort(graph: dict[int, list[int]]) -> list[int] | None:
             indegree[i] += 1
 
     # Add all vertices with 0 indegree to the queue
-    for i in range(len(indegree)):
-        if indegree[i] == 0:
-            queue.append(i)
+    for vertex, count in indegree.items():
+        if count == 0:
+            queue.append(vertex)
 
     # Perform BFS
     while queue:
-        vertex = queue.pop(0)
+        vertex = queue.popleft()
         processed_vertices_count += 1
         topo_order.append(vertex)
 

machine_learning/xgboost_classifier.py

@@ -1,14 +1,12 @@
-"""Matrix Exponentiation"""
-
-import timeit
-
 """
 Matrix Exponentiation is a technique to solve linear recurrences in logarithmic time.
 You read more about it here:
 https://zobayer.blogspot.com/2010/11/matrix-exponentiation.html
 https://www.hackerearth.com/practice/notes/matrix-exponentiation-1/
 """
 
+import timeit
+
 
 class Matrix:
     def __init__(self, arg: list[list] | int) -> None:

machine_learning/xgboost_regressor.py

@@ -27,7 +27,6 @@ dependencies = [
   "statsmodels>=0.14.4",
   "sympy>=1.13.3",
   "typing-extensions>=4.12.2",
-  "xgboost>=2.1.3",
 ]
 
 [dependency-groups]
@@ -174,7 +173,9 @@ lint.pylint.max-returns = 8  # default: 6
 lint.pylint.max-statements = 88  # default: 50
 
 [tool.codespell]
-ignore-words-list = "3rt,abd,aer,ans,bitap,crate,damon,fo,followings,hist,iff,kwanza,manuel,mater,secant,som,sur,tim,toi,zar"
+ignore-words-list = """\
+  3rt,abd,aer,ans,bitap,crate,damon,fo,followings,hist,iff,kwanza,manuel,mater,secant,som,sur,tim,toi,zar\
+  """
 skip = """\
   ./.*,*.json,*.lock,ciphers/prehistoric_men.txt,project_euler/problem_022/p022_names.txt,pyproject.toml,strings/dictio\
   nary.txt,strings/words.txt\