Add topological sort using DFS and Kahn's algorithm #14086
Conversation
algorithms-keeper
bot
added
require tests
![algorithms-keeper[bot]](https://avatars.githubusercontent.com/in/235834?s=60&v=4){kind=small}
There was a problem hiding this comment.
Click here to look at the relevant links ⬇️
🔗 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 commands and options
algorithms-keeper actions can be triggered by commenting on this PR:
@algorithms-keeper reviewto trigger the checks for only added pull request files@algorithms-keeper review-allto 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.
| visited = [0] * vertices | ||
| result: List[int] = [] | ||
|
|
||
| def dfs(node: int) -> None: |
There was a problem hiding this comment.
As there is no test file in this pull request nor any test function or class in the file data_structures/sort/topological_sort.py, please provide doctest for the function dfs
algorithms-keeper
bot
removed
the
require tests
algorithms-keeper
bot
added
the
require tests
There was a problem hiding this comment.
Click here to look at the relevant links ⬇️
🔗 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 commands and options
algorithms-keeper actions can be triggered by commenting on this PR:
@algorithms-keeper reviewto trigger the checks for only added pull request files@algorithms-keeper review-allto 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.
| from collections import deque | ||
|
|
||
|
|
||
| def _dfs( |
There was a problem hiding this comment.
As there is no test file in this pull request nor any test function or class in the file data_structures/sort/topological_sort.py, please provide doctest for the function _dfs
| result.append(node) | ||
|
|
||
|
|
||
| def topological_sort_dfs(vertices: int, edges: list[list[int]]) -> list[int]: |
There was a problem hiding this comment.
As there is no test file in this pull request nor any test function or class in the file data_structures/sort/topological_sort.py, please provide doctest for the function topological_sort_dfs
| return result[::-1] | ||
|
|
||
|
|
||
| def topological_sort_kahn(vertices: int, edges: list[list[int]]) -> list[int]: |
There was a problem hiding this comment.
As there is no test file in this pull request nor any test function or class in the file data_structures/sort/topological_sort.py, please provide doctest for the function topological_sort_kahn
There was a problem hiding this comment.
- The current implementation risks an
IndexErrorif an edge references a vertex index outside the range$[0, \text{vertices}-1]$ . Adding validation ensures the algorithm fails gracefully with a clear message. - Using
collections.defaultdict(list)for the graph construction is more idiomatic for sparse graphs. It simplifies the initialization logic and handles missing keys more gracefully than a pre-allocated list of lists.
2 participants
Describe your change:
This pull request adds a Topological Sort implementation using both:
The implementation includes cycle detection, clear documentation, and example usage.
Topological sorting is applicable to Directed Acyclic Graphs (DAGs).
Checklist: