Add topological sort using DFS and Kahn's algorithm#14086
Add topological sort using DFS and Kahn's algorithm#1408616Prithvi wants to merge 8 commits intoTheAlgorithms:masterfrom
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require tests
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| visited = [0] * vertices | ||
| result: List[int] = [] | ||
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| def dfs(node: int) -> None: |
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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
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require tests
algorithms-keeper
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require tests
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| from collections import deque | ||
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| def _dfs( |
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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) | ||
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| def topological_sort_dfs(vertices: int, edges: list[list[int]]) -> list[int]: |
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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] | ||
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| def topological_sort_kahn(vertices: int, edges: list[list[int]]) -> list[int]: |
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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
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- 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.
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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: