Add a utility for finding minimal topological sorts#6884
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Reuse the code implementing Kahn's topological sort algorithm with a new configuration that uses a min-heap to always choose the best available element. Also add wrapper utilities that can find topological sorts of graphs with arbitrary element types, not just indices.
kripken
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Aug 29, 2024
src/support/topological_orders.h
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| // the indices of its children, which will appear after it in the order. | ||
| TopologicalOrders(const std::vector<std::vector<size_t>>& graph); | ||
| TopologicalOrders(const std::vector<std::vector<size_t>>& graph) | ||
| : TopologicalOrders(graph, false) {} |
| const std::vector<size_t>& operator*() const { | ||
| return TopologicalOrders::operator*(); | ||
| } | ||
| }; |
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This constructor is identical to the parent, and this operator doesn't seem to modify anything either - I am sure I'm missing something?
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Nope, this is providing a small subset of the functionality of the superclass, packaged under a different name that is more appropriate for the common case of needing just one topological sort.
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Ah, thanks... I was missing the word "private" on line 108. Makes sense now.
| Graph graph(3); | ||
| graph[2].push_back(1); | ||
| std::vector<size_t> expected{0, 2, 1}; | ||
| EXPECT_EQ(*MinTopologicalSort(graph), expected); |
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Maybe add comments to these, e.g. for this one IIUC the point is to show that 2 is before 1, and the unconstrained 0 is smaller so it appears before them both.
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Reuse the code implementing Kahn's topological sort algorithm with a new
configuration that uses a min-heap to always choose the best available
element.
Also add wrapper utilities that can find topological sorts of graphs
with arbitrary element types, not just indices.