82 lines
3.1 KiB
C
82 lines
3.1 KiB
C
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#ifndef INCLUDED_C_BELLMANFORDSP_H
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#define INCLUDED_C_BELLMANFORDSP_H
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#ifndef INCLUDED_C_EDGEWEIGHTEDDIGRAPH_H
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#include <c_EdgeWeightedDigraph.h>
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#endif /*INCLUDED_C_EDGEWEIGHTEDDIGRAPH_H*/
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#ifndef INCLUDED_C_VERTEXIDLIST_H
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#include <c_VertexIdList.h>
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#endif /*INCLUDED_C_VERTEXIDLIST_H*/
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/* ------------------------------------------------------------------------------------------------------------------ */
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/* */
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typedef struct {
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c_size_t* edge_to; /* edge_to[w] = entering directed edge_id on shortest path to w */
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c_size_t* from_vertex; /* from_vertex[w] = source vertex parent link on path to w */
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double* dist_to; /* dist_to[w] = cumulative distance from source s to w */
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c_bool_t* on_queue; /* on_queue[v] = is vertex v currently sitting inside the processing FIFO queue */
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c_VertexIdList_t cycle; /* Catches and stores the negative cycle path sequence if found */
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c_size_t cost_counter; /* Tracks number of relax calls to gauge periodic cycle check steps */
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c_size_t s; /* The source vertex index */
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c_size_t V; /* Total number of vertices in the digraph */
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c_Allocator_t allocator; /* Deep copy of the user-provided allocator */
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} c_BellmanFordSP_t;
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/* ------------------------------------------------------------------------------------------------------------------ */
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/* */
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/**
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* @brief Computes a shortest-paths tree from the source vertex 's' in the edge-weighted digraph.
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* @param allocator Explicit allocator context used to configure internal tracking state memory
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*/
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c_err_t c_BellmanFordSP_Init(c_BellmanFordSP_t* self, c_EdgeWeightedDigraph_t* graph, c_size_t s, c_Allocator_t* allocator);
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/**
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* @brief Releases internal tracking buffers safely.
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*/
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void c_BellmanFordSP_Destroy(c_BellmanFordSP_t* self);
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/**
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* @brief Is there a directed path from the source vertex 's' to vertex 'v'?
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*/
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C_STATIC_FORCE_INLINE
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c_bool_t c_BellmanFordSP_HasPathTo(c_BellmanFordSP_t* self, c_size_t v) {
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if (!self || v >= self->V || !self->dist_to) return C_FALSE;
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return self->dist_to[v] < DBL_MAX;
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}
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/**
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* @brief Returns the distance of the shortest path from the source vertex 's' to vertex 'v'.
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*/
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C_STATIC_FORCE_INLINE
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double c_BellmanFordSP_DistTo(c_BellmanFordSP_t* self, c_size_t v) {
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if (!self || v >= self->V || !self->dist_to) return DBL_MAX;
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return self->dist_to[v];
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}
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/**
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* @brief Does the edge-weighted digraph contain a negative cycle reachable from the source vertex?
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*/
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C_STATIC_FORCE_INLINE
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c_bool_t c_BellmanFordSP_HasNegativeCycle(c_BellmanFordSP_t* self) {
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if (!self) return C_FALSE;
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return !c_VertexIdList_IsEmpty(&self->cycle);
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}
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/**
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* @brief Reconstructs the exact shortest path from the source vertex 's' to vertex 'v' and appends it to out_path.
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*/
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c_err_t c_BellmanFordSP_PathTo(c_BellmanFordSP_t* self, c_size_t v, c_VertexIdList_t* out_path);
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/**
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* @brief Extracts the vertices forming the detected negative cycle loop if present.
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*/
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c_err_t c_BellmanFordSP_GetNegativeCycle(c_BellmanFordSP_t* self, c_VertexIdList_t* out_cycle);
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#endif /*INCLUDED_C_BELLMANFORDSP_H*/
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