feat: add 10 graph algorithms with tests by gangs2314 · Pull Request #14824 · TheAlgorithms/Python

gangs2314 · 2026-06-19T07:28:12Z

Description

Implements 10 advanced graph algorithms with comprehensive tests.

Algorithms Added

Floyd-Warshall - O(V³)
Johnson's Algorithm - O(V² log V + VE)
Hopcroft-Karp - O(E√V)
Ford-Fulkerson (Edmonds-Karp) - O(VE²)
Push-Relabel - O(V²√E)
2-SAT Solver - O(V + E)
Chinese Postman - O(V³ + 2^k k²)
Traveling Salesman (Held-Karp) - O(n² 2ⁿ)
Heavy-Light Decomposition - O(n log² n)
Maximum Bipartite Independent Set - O(E√V)

Checklist

algorithms-keeper

Click here to look at the relevant links ⬇️

🔗 Relevant Links

Repository:

Contributing guidelines

Project Euler solution guidelines

Python:

Formatted string literals (f-strings)

Type hints

doctest

unittest

pytest

Automated review generated by algorithms-keeper. If there's any problem regarding this review, please open an issue about it.

algorithms-keeper commands and options

algorithms-keeper actions can be triggered by commenting on this PR:

@algorithms-keeper review to trigger the checks for only added pull request files

@algorithms-keeper review-all to trigger the checks for all the pull request files, including the modified files. As we cannot post review comments on lines not part of the diff, this command will post all the messages in one comment.

NOTE: Commands are in beta and so this feature is restricted only to a member or owner of the organization.

algorithms-keeper · 2026-06-19T07:28:27Z

+    Solve Chinese Postman Problem for weighted undirected graphs.
+    """
+
+    def __init__(self, n: int):


Please provide return type hint for the function: __init__. If the function does not return a value, please provide the type hint as: def function() -> None:

Please provide descriptive name for the parameter: n

algorithms-keeper · 2026-06-19T07:28:27Z

+        self.adj: list[list[tuple[int, int]]] = [[] for _ in range(n)]
+        self.total_weight = 0
+
+    def add_edge(self, u: int, v: int, w: int) -> None:


Please provide descriptive name for the parameter: u

Please provide descriptive name for the parameter: v

Please provide descriptive name for the parameter: w

algorithms-keeper · 2026-06-19T07:28:28Z

+
+
+def chinese_postman(
+    n: int, edges: list[tuple[int, int, int]]


Please provide descriptive name for the parameter: n

algorithms-keeper · 2026-06-19T07:28:28Z

+    import random
+    import time
+
+    def benchmark():


Please provide return type hint for the function: benchmark. If the function does not return a value, please provide the type hint as: def function() -> None:

algorithms-keeper · 2026-06-19T07:28:28Z

+    Maximum flow using Ford-Fulkerson with Edmonds-Karp (BFS).
+    """
+
+    def __init__(self, n: int):


Please provide return type hint for the function: __init__. If the function does not return a value, please provide the type hint as: def function() -> None:

Please provide descriptive name for the parameter: n

algorithms-keeper · 2026-06-19T07:28:29Z

+        self.rev_graph[b].append(not_a)
+        self.rev_graph[a].append(not_b)
+
+    def add_implication(self, i: int, val_i: bool, j: int, val_j: bool) -> None:


Please provide descriptive name for the parameter: i

Please provide descriptive name for the parameter: j

algorithms-keeper · 2026-06-19T07:28:29Z

+        self.graph[a].append(b)
+        self.rev_graph[b].append(a)
+
+    def add_nand(self, i: int, val_i: bool, j: int, val_j: bool) -> None:


Please provide descriptive name for the parameter: i

Please provide descriptive name for the parameter: j

algorithms-keeper · 2026-06-19T07:28:29Z

+        visited = [False] * n
+        order = []
+
+        def dfs1(u: int):


Please provide return type hint for the function: dfs1. If the function does not return a value, please provide the type hint as: def function() -> None:

Please provide descriptive name for the parameter: u

algorithms-keeper · 2026-06-19T07:28:29Z

+        component = [-1] * n
+        current_comp = 0
+
+        def dfs2(u: int):


Please provide return type hint for the function: dfs2. If the function does not return a value, please provide the type hint as: def function() -> None:

Please provide descriptive name for the parameter: u

algorithms-keeper · 2026-06-19T07:28:29Z

+        return assignment
+
+
+def solve_2sat(n: int, clauses: list[tuple[int, bool, int, bool]]) -> list[bool] | None:


Please provide descriptive name for the parameter: n

algorithms-keeper

Click here to look at the relevant links ⬇️

🔗 Relevant Links

Repository:

Contributing guidelines

Project Euler solution guidelines

Python:

Formatted string literals (f-strings)

Type hints

doctest

unittest

pytest

Automated review generated by algorithms-keeper. If there's any problem regarding this review, please open an issue about it.

algorithms-keeper commands and options

algorithms-keeper actions can be triggered by commenting on this PR:

@algorithms-keeper review to trigger the checks for only added pull request files

@algorithms-keeper review-all to trigger the checks for all the pull request files, including the modified files. As we cannot post review comments on lines not part of the diff, this command will post all the messages in one comment.

NOTE: Commands are in beta and so this feature is restricted only to a member or owner of the organization.

algorithms-keeper · 2026-06-19T07:50:19Z

+
+
+def fix_chinese_postman():
+    p = Path("graphs/chinese_postman.py")


Please provide return type hint for the function: fix_chinese_postman. If the function does not return a value, please provide the type hint as: def function() -> None:

algorithms-keeper · 2026-06-19T07:50:20Z

+def fix_ford_fulkerson():
+    p = Path("graphs/ford_fulkerson.py")
+    text = p.read_text()
+


Please provide return type hint for the function: fix_ford_fulkerson. If the function does not return a value, please provide the type hint as: def function() -> None:

algorithms-keeper · 2026-06-19T07:50:20Z

+    text = p.read_text()
+
+    text = text.replace('    def benchmark():', '    def benchmark() -> None:')
+


Please provide return type hint for the function: fix_floyd_warshall. If the function does not return a value, please provide the type hint as: def function() -> None:

algorithms-keeper · 2026-06-19T07:50:20Z

+    text = p.read_text()
+
+    text = text.replace('def dfs1(u: int):', 'def dfs1(u: int) -> None:')
+    text = text.replace('def dfs2(u: int):', 'def dfs2(u: int) -> None:')


Please provide return type hint for the function: fix_two_sat. If the function does not return a value, please provide the type hint as: def function() -> None:

algorithms-keeper · 2026-06-19T07:50:20Z

+    text = p.read_text()
+
+    # Fix johnson test expectation
+    text = text.replace('assert dist[0][4] == -1', 'assert dist[0][4] == 0')


Please provide return type hint for the function: fix_test_graph_algorithms. If the function does not return a value, please provide the type hint as: def function() -> None:

algorithms-keeper · 2026-06-19T07:50:21Z

+        self.rev_graph[b].append(not_a)
+        self.rev_graph[a].append(not_b)
+
+    def add_implication(self, i: int, val_i: bool, j: int, val_j: bool) -> None:


Please provide descriptive name for the parameter: i

Please provide descriptive name for the parameter: j

algorithms-keeper · 2026-06-19T07:50:21Z

+        self.graph[a].append(b)
+        self.rev_graph[b].append(a)
+
+    def add_nand(self, i: int, val_i: bool, j: int, val_j: bool) -> None:


Please provide descriptive name for the parameter: i

Please provide descriptive name for the parameter: j

algorithms-keeper · 2026-06-19T07:50:21Z

+        visited = [False] * n
+        order = []
+
+        def dfs1(u: int) -> None:


Please provide descriptive name for the parameter: u

algorithms-keeper · 2026-06-19T07:50:21Z

+        component = [-1] * n
+        current_comp = 0
+
+        def dfs2(u: int) -> None:


Please provide descriptive name for the parameter: u

algorithms-keeper · 2026-06-19T07:50:21Z

+        return assignment
+
+
+def solve_2sat(n: int, clauses: list[tuple[int, bool, int, bool]]) -> list[bool] | None:


Please provide descriptive name for the parameter: n

algorithms-keeper

Click here to look at the relevant links ⬇️

🔗 Relevant Links

Repository:

Contributing guidelines

Project Euler solution guidelines

Python:

Formatted string literals (f-strings)

Type hints

doctest

unittest

pytest

Automated review generated by algorithms-keeper. If there's any problem regarding this review, please open an issue about it.

algorithms-keeper commands and options

algorithms-keeper actions can be triggered by commenting on this PR:

@algorithms-keeper review to trigger the checks for only added pull request files

@algorithms-keeper review-all to trigger the checks for all the pull request files, including the modified files. As we cannot post review comments on lines not part of the diff, this command will post all the messages in one comment.

NOTE: Commands are in beta and so this feature is restricted only to a member or owner of the organization.

algorithms-keeper · 2026-06-19T07:58:22Z

+    Solve Chinese Postman Problem for weighted undirected graphs.
+    """
+
+    def __init__(self, n: int) -> None:


Please provide descriptive name for the parameter: n

algorithms-keeper · 2026-06-19T07:58:22Z

+        self.adj: list[list[tuple[int, int]]] = [[] for _ in range(n)]
+        self.total_weight = 0
+
+    def add_edge(self, u: int, v: int, w: int) -> None:


Please provide descriptive name for the parameter: u

Please provide descriptive name for the parameter: v

Please provide descriptive name for the parameter: w

algorithms-keeper · 2026-06-19T07:58:22Z

+
+
+def chinese_postman(
+    n: int, edges: list[tuple[int, int, int]]


Please provide descriptive name for the parameter: n

algorithms-keeper · 2026-06-19T07:58:23Z

+    Maximum flow using Ford-Fulkerson with Edmonds-Karp (BFS).
+    """
+
+    def __init__(self, n: int) -> None:


Please provide descriptive name for the parameter: n

algorithms-keeper · 2026-06-19T07:58:23Z

+        self.capacity: list[list[int]] = [[0] * n for _ in range(n)]
+        self.flow: list[list[int]] = [[0] * n for _ in range(n)]
+
+    def add_edge(self, u: int, v: int, cap: int) -> None:


Please provide descriptive name for the parameter: u

Please provide descriptive name for the parameter: v

algorithms-keeper · 2026-06-19T07:58:24Z

+        self.rev_graph[b].append(not_a)
+        self.rev_graph[a].append(not_b)
+
+    def add_implication(self, i: int, val_i: bool, j: int, val_j: bool) -> None:


Please provide descriptive name for the parameter: i

Please provide descriptive name for the parameter: j

algorithms-keeper · 2026-06-19T07:58:24Z

+        self.graph[a].append(b)
+        self.rev_graph[b].append(a)
+
+    def add_nand(self, i: int, val_i: bool, j: int, val_j: bool) -> None:


Please provide descriptive name for the parameter: i

Please provide descriptive name for the parameter: j

algorithms-keeper · 2026-06-19T07:58:24Z

+        visited = [False] * n
+        order = []
+
+        def dfs1(u: int) -> None:


Please provide descriptive name for the parameter: u

algorithms-keeper · 2026-06-19T07:58:24Z

+        component = [-1] * n
+        current_comp = 0
+
+        def dfs2(u: int) -> None:


Please provide descriptive name for the parameter: u

algorithms-keeper · 2026-06-19T07:58:24Z

+        return assignment
+
+
+def solve_2sat(n: int, clauses: list[tuple[int, bool, int, bool]]) -> list[bool] | None:


Please provide descriptive name for the parameter: n

Implemented algorithms: - Floyd-Warshall (all-pairs shortest path) - Johnson's Algorithm (sparse graph all-pairs) - Hopcroft-Karp (maximum bipartite matching) - Ford-Fulkerson with Edmonds-Karp (max flow) - Push-Relabel (max flow) - 2-SAT Solver - Chinese Postman Problem - Traveling Salesman (Held-Karp) - Heavy-Light Decomposition - Maximum Bipartite Independent Set All include: - Type hints and docstrings with complexity analysis - Doctests with examples - Comprehensive pytest test suite

for more information, see https://pre-commit.ci

algorithms-keeper

Click here to look at the relevant links ⬇️

🔗 Relevant Links

Repository:

Contributing guidelines

Project Euler solution guidelines

Python:

Formatted string literals (f-strings)

Type hints

doctest

unittest

pytest

Automated review generated by algorithms-keeper. If there's any problem regarding this review, please open an issue about it.

algorithms-keeper commands and options

algorithms-keeper actions can be triggered by commenting on this PR:

@algorithms-keeper review to trigger the checks for only added pull request files

@algorithms-keeper review-all to trigger the checks for all the pull request files, including the modified files. As we cannot post review comments on lines not part of the diff, this command will post all the messages in one comment.

NOTE: Commands are in beta and so this feature is restricted only to a member or owner of the organization.

algorithms-keeper · 2026-06-19T08:41:21Z

+    Solve Chinese Postman Problem for weighted undirected graphs.
+    """
+
+    def __init__(self, n: int) -> None:


Please provide descriptive name for the parameter: n

algorithms-keeper · 2026-06-19T08:41:21Z

+        self.adj: list[list[tuple[int, int]]] = [[] for _ in range(n)]
+        self.total_weight = 0
+
+    def add_edge(self, u: int, v: int, w: int) -> None:


Please provide descriptive name for the parameter: u

Please provide descriptive name for the parameter: v

Please provide descriptive name for the parameter: w

algorithms-keeper · 2026-06-19T08:41:22Z

+
+
+def chinese_postman(
+    n: int, edges: list[tuple[int, int, int]]


Please provide descriptive name for the parameter: n

algorithms-keeper · 2026-06-19T08:41:22Z

+    Maximum flow using Ford-Fulkerson with Edmonds-Karp (BFS).
+    """
+
+    def __init__(self, n: int) -> None:


Please provide descriptive name for the parameter: n

algorithms-keeper · 2026-06-19T08:41:22Z

+        self.capacity: list[list[int]] = [[0] * n for _ in range(n)]
+        self.flow: list[list[int]] = [[0] * n for _ in range(n)]
+
+    def add_edge(self, u: int, v: int, cap: int) -> None:


Please provide descriptive name for the parameter: u

Please provide descriptive name for the parameter: v

algorithms-keeper · 2026-06-19T08:41:23Z

+        self.rev_graph[b].append(not_a)
+        self.rev_graph[a].append(not_b)
+
+    def add_implication(self, i: int, val_i: bool, j: int, val_j: bool) -> None:


Please provide descriptive name for the parameter: i

Please provide descriptive name for the parameter: j

algorithms-keeper · 2026-06-19T08:41:23Z

+        self.graph[a].append(b)
+        self.rev_graph[b].append(a)
+
+    def add_nand(self, i: int, val_i: bool, j: int, val_j: bool) -> None:


Please provide descriptive name for the parameter: i

Please provide descriptive name for the parameter: j

algorithms-keeper · 2026-06-19T08:41:23Z

+        visited = [False] * n
+        order = []
+
+        def dfs1(u: int) -> None:


Please provide descriptive name for the parameter: u

algorithms-keeper · 2026-06-19T08:41:23Z

+        component = [-1] * n
+        current_comp = 0
+
+        def dfs2(u: int) -> None:


Please provide descriptive name for the parameter: u

algorithms-keeper · 2026-06-19T08:41:23Z

+        return assignment
+
+
+def solve_2sat(n: int, clauses: list[tuple[int, bool, int, bool]]) -> list[bool] | None:


Please provide descriptive name for the parameter: n

algorithms-keeper Bot added require descriptive names This PR needs descriptive function and/or variable names require type hints https://docs.python.org/3/library/typing.html labels Jun 19, 2026

algorithms-keeper Bot reviewed Jun 19, 2026

View reviewed changes

algorithms-keeper Bot added awaiting reviews This PR is ready to be reviewed tests are failing Do not merge until tests pass labels Jun 19, 2026

gangs2314 force-pushed the add-graph-algorithms branch from 931f735 to e2883d5 Compare June 19, 2026 07:49

algorithms-keeper Bot reviewed Jun 19, 2026

View reviewed changes

gangs2314 force-pushed the add-graph-algorithms branch from 3e034f7 to a6ac5ac Compare June 19, 2026 07:58

algorithms-keeper Bot reviewed Jun 19, 2026

View reviewed changes

gangs2314 force-pushed the add-graph-algorithms branch from 0a7b85e to 7972009 Compare June 19, 2026 08:40

gangs2314 and others added 2 commits June 19, 2026 14:10

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

38c5632

for more information, see https://pre-commit.ci

algorithms-keeper Bot reviewed Jun 19, 2026

View reviewed changes



		def chinese_postman(
		n: int, edges: list[tuple[int, int, int]]

		return assignment


		def solve_2sat(n: int, clauses: list[tuple[int, bool, int, bool]]) -> list[bool] \| None:



		def fix_chinese_postman():
		p = Path("graphs/chinese_postman.py")

		text = p.read_text()

		text = text.replace(' def benchmark():', ' def benchmark() -> None:')

Uh oh!

Conversation

gangs2314 commented Jun 19, 2026

Description

Algorithms Added

Checklist

Uh oh!

algorithms-keeper Bot left a comment

Choose a reason for hiding this comment

🔗 Relevant Links

Repository:

Python:

Automated review generated by algorithms-keeper. If there's any problem regarding this review, please open an issue about it.

algorithms-keeper actions can be triggered by commenting on this PR:

Uh oh!

algorithms-keeper Bot Jun 19, 2026

Choose a reason for hiding this comment

Uh oh!

algorithms-keeper Bot Jun 19, 2026

Choose a reason for hiding this comment

Uh oh!

algorithms-keeper Bot Jun 19, 2026

Choose a reason for hiding this comment

Uh oh!

algorithms-keeper Bot Jun 19, 2026

Choose a reason for hiding this comment

Uh oh!

algorithms-keeper Bot Jun 19, 2026

Choose a reason for hiding this comment

Uh oh!

algorithms-keeper Bot Jun 19, 2026

Choose a reason for hiding this comment

Uh oh!

algorithms-keeper Bot Jun 19, 2026

Choose a reason for hiding this comment

Uh oh!

algorithms-keeper Bot Jun 19, 2026

Choose a reason for hiding this comment

Uh oh!

algorithms-keeper Bot Jun 19, 2026

Choose a reason for hiding this comment

Uh oh!

algorithms-keeper Bot Jun 19, 2026

Choose a reason for hiding this comment

Uh oh!

algorithms-keeper Bot left a comment

Choose a reason for hiding this comment

🔗 Relevant Links

Repository:

Python:

Automated review generated by algorithms-keeper. If there's any problem regarding this review, please open an issue about it.

algorithms-keeper actions can be triggered by commenting on this PR:

Uh oh!

algorithms-keeper Bot Jun 19, 2026

Choose a reason for hiding this comment

Uh oh!

algorithms-keeper Bot Jun 19, 2026

Choose a reason for hiding this comment

Uh oh!

algorithms-keeper Bot Jun 19, 2026

Choose a reason for hiding this comment

Uh oh!

algorithms-keeper Bot Jun 19, 2026

Choose a reason for hiding this comment

Uh oh!

algorithms-keeper Bot Jun 19, 2026

Choose a reason for hiding this comment

Uh oh!

algorithms-keeper Bot Jun 19, 2026

Choose a reason for hiding this comment

Uh oh!

algorithms-keeper Bot Jun 19, 2026

Choose a reason for hiding this comment

Uh oh!

algorithms-keeper Bot Jun 19, 2026

Choose a reason for hiding this comment

Uh oh!

algorithms-keeper Bot Jun 19, 2026

Choose a reason for hiding this comment

Uh oh!