Merge pull request #100 from stdgraph/bfs

Add find_negative_cycle for Bellman-Ford
Move Topological Sort to Traversal section

D3128_Algorithms/src/bellman_shortest_dists.hpp

@@ -4,14 +4,16 @@ template <index_adjacency_list G,
  class Visitor = bellman_visitor_base<G>,
  class Compare = less<ranges::range_value_t<Distances>>,
  class Combine = plus<ranges::range_value_t<Distances>>>
-requires is_arithmetic_v<ranges::range_value_t<Distances>> && //
- basic_edge_weight_function<G, WF, ranges::range_value_t<Distances>, Compare, Combine> &&
+requires is_arithmetic_v<ranges::range_value_t<Distances>> && 
+ ranges::sized_range<Distances> && 
+ basic_edge_weight_function<G, WF, ranges::range_value_t<Distances>, Compare, Combine> && 
  bellman_visitor<G, Visitor>
-bool bellman_ford_shortest_distances(
+optional<vertex_id_t<G>> bellman_ford_shortest_distances(
  G& g,
  const vertex_id_t<G> source,
  Distances& distances,
- WF&& weight = [](edge_reference_t<G> uv) { return ranges::range_value_t<Distances>(1); },
+ WF&& weight =
+ [](edge_reference_t<G> uv) { return ranges::range_value_t<Distances>(1); }, // default weight(uv) -> 1
  Visitor&& visitor = bellman_visitor_base<G>(),
  Compare&& compare = less<ranges::range_value_t<Distances>>(),
  Combine&& combine = plus<ranges::range_value_t<Distances>>());

D3128_Algorithms/src/bellman_shortest_dists_multi.hpp

@@ -5,14 +5,17 @@ template <index_adjacency_list G,
  class Visitor = bellman_visitor_base<G>,
  class Compare = less<ranges::range_value_t<Distances>>,
  class Combine = plus<ranges::range_value_t<Distances>>>
-requires convertible_to<ranges::range_value_t<Sources>, vertex_id_t<G>> &&
- is_arithmetic_v<ranges::range_value_t<Distances>> &&
- basic_edge_weight_function<G, WF, ranges::range_value_t<Distances>, Compare, Combine>
-bool bellman_ford_shortest_distances(
+requires convertible_to<ranges::range_value_t<Sources>, vertex_id_t<G>> && //
+ is_arithmetic_v<ranges::range_value_t<Distances>> && //
+ ranges::sized_range<Distances> && //
+ basic_edge_weight_function<G, WF, ranges::range_value_t<Distances>, Compare, Combine> &&
+ bellman_visitor<G, Visitor>
+optional<vertex_id_t<G>> bellman_ford_shortest_distances(
  G& g,
  const Sources& sources,
  Distances& distances,
- WF&& weight = [](edge_reference_t<G> uv) { return ranges::range_value_t<Distances>(1); },
+ WF&& weight =
+ [](edge_reference_t<G> uv) { return ranges::range_value_t<Distances>(1); }, // default weight(uv) -> 1
  Visitor&& visitor = bellman_visitor_base<G>(),
  Compare&& compare = less<ranges::range_value_t<Distances>>(),
  Combine&& combine = plus<ranges::range_value_t<Distances>>());

D3128_Algorithms/src/bellman_shortest_paths.hpp

@@ -5,16 +5,19 @@ template <index_adjacency_list G,
  class Visitor = bellman_visitor_base<G>,
  class Compare = less<ranges::range_value_t<Distances>>,
  class Combine = plus<ranges::range_value_t<Distances>>>
-requires is_arithmetic_v<ranges::range_value_t<Distances>> &&
- convertible_to<vertex_id_t<G>, ranges::range_value_t<Predecessors>> &&
+requires is_arithmetic_v<ranges::range_value_t<Distances>> && 
+ convertible_to<vertex_id_t<G>, ranges::range_value_t<Predecessors>> && 
+ ranges::sized_range<Distances> && 
+ ranges::sized_range<Predecessors> && 
  basic_edge_weight_function<G, WF, ranges::range_value_t<Distances>, Compare, Combine> &&
  bellman_visitor<G, Visitor>
-bool bellman_ford_shortest_paths(
+optional<vertex_id_t<G>> bellman_ford_shortest_paths(
  G& g,
  const vertex_id_t<G> source,
  Distances& distances,
  Predecessors& predecessor,
- WF&& weight = [](edge_reference_t<G> uv) { return ranges::range_value_t<Distances>(1); },
+ WF&& weight =
+ [](edge_reference_t<G> uv) { return ranges::range_value_t<Distances>(1); }, // default weight(uv) -> 1
  Visitor&& visitor = bellman_visitor_base<G>(),
  Compare&& compare = less<ranges::range_value_t<Distances>>(),
  Combine&& combine = plus<ranges::range_value_t<Distances>>());

D3128_Algorithms/src/bellman_shortest_paths_multi.hpp

@@ -6,16 +6,20 @@ template <index_adjacency_list G,
  class Visitor = bellman_visitor_base<G>,
  class Compare = less<ranges::range_value_t<Distances>>,
  class Combine = plus<ranges::range_value_t<Distances>>>
-requires convertible_to<ranges::range_value_t<Sources>, vertex_id_t<G>> &&
- is_arithmetic_v<ranges::range_value_t<Distances>> &&
- convertible_to<vertex_id_t<G>, ranges::range_value_t<Predecessors>> &&
- basic_edge_weight_function<G, WF, ranges::range_value_t<Distances>, Compare, Combine>
-bool bellman_ford_shortest_paths(
+requires convertible_to<ranges::range_value_t<Sources>, vertex_id_t<G>> && 
+ is_arithmetic_v<ranges::range_value_t<Distances>> && 
+ convertible_to<vertex_id_t<G>, ranges::range_value_t<Predecessors>> && 
+ ranges::sized_range<Distances> && 
+ ranges::sized_range<Predecessors> && 
+ basic_edge_weight_function<G, WF, ranges::range_value_t<Distances>, Compare, Combine> &&
+ bellman_visitor<G, Visitor>
+optional<vertex_id_t<G>> bellman_ford_shortest_paths(
  G& g,
  const Sources& sources,
  Distances& distances,
  Predecessors& predecessor,
- WF&& weight = [](edge_reference_t<G> uv) { return ranges::range_value_t<Distances>(1); },
+ WF&& weight =
+ [](edge_reference_t<G> uv) { return ranges::range_value_t<Distances>(1); }, // default weight(uv) -> 1
  Visitor&& visitor = bellman_visitor_base<G>(),
  Compare&& compare = less<ranges::range_value_t<Distances>>(),
  Combine&& combine = plus<ranges::range_value_t<Distances>>());

D3128_Algorithms/src/breadth_first_search_helpers.hpp

@@ -15,8 +15,5 @@ constexpr void init_breadth_first_search(Distances& distances) {
 
 template <class Predecessors>
 constexpr void init_breadth_first_search(Predecessors& predecessors) {
- // exposition only
- size_t i = 0;
- for(auto& pred : predecessors)
- pred = i++; 
+ ranges::iota(predecessors, 0); // exposition only
 }

D3128_Algorithms/src/dijkstra_shortest_dists.hpp

@@ -5,13 +5,14 @@ template <index_adjacency_list G,
  class Compare = less<ranges::range_value_t<Distances>>,
  class Combine = plus<ranges::range_value_t<Distances>>>
 requires is_arithmetic_v<ranges::range_value_t<Distances>> && //
+ ranges::sized_range<Distances> && //
  basic_edge_weight_function<G, WF, ranges::range_value_t<Distances>, Compare, Combine> &&
  dijkstra_visitor<G, Visitor>
 void dijkstra_shortest_distances(
  G& g,
  const vertex_id_t<G> source,
  Distances& distances,
- WF&& weight  = [](edge_reference_t<G> uv) { return ranges::range_value_t<Distances>(1); },
+ WF&& weight = [](edge_reference_t<G> uv) { return ranges::range_value_t<Distances>(1); },
  Visitor&& visitor = dijkstra_visitor_base<G>(),
  Compare&& compare = less<ranges::range_value_t<Distances>>(),
  Combine&& combine = plus<ranges::range_value_t<Distances>>());

D3128_Algorithms/src/dijkstra_shortest_dists_multi.hpp

@@ -5,14 +5,16 @@ template <index_adjacency_list G,
  class Visitor = dijkstra_visitor_base<G>,
  class Compare = less<ranges::range_value_t<Distances>>,
  class Combine = plus<ranges::range_value_t<Distances>>>
-requires convertible_to<ranges::range_value_t<Sources>, vertex_id_t<G>> &&
- is_arithmetic_v<ranges::range_value_t<Distances>> &&
- basic_edge_weight_function<G, WF, ranges::range_value_t<Distances>, Compare, Combine>
+requires convertible_to<ranges::range_value_t<Sources>, vertex_id_t<G>> && //
+ ranges::sized_range<Distances> && //
+ is_arithmetic_v<ranges::range_value_t<Distances>> && //
+ basic_edge_weight_function<G, WF, ranges::range_value_t<Distances>, Compare, Combine> && 
+ dijkstra_visitor<G, Visitor>
 void dijkstra_shortest_distances(
  G& g,
  const Sources& sources,
  Distances& distances,
- WF&& weight  = [](edge_reference_t<G> uv) { return ranges::range_value_t<Distances>(1); },
+ WF&& weight = [](edge_reference_t<G> uv) { return ranges::range_value_t<Distances>(1); },
  Visitor&& visitor = dijkstra_visitor_base<G>(),
  Compare&& compare = less<ranges::range_value_t<Distances>>(),
  Combine&& combine = plus<ranges::range_value_t<Distances>>());

D3128_Algorithms/src/dijkstra_shortest_paths.hpp

@@ -1,11 +1,13 @@
 template <index_adjacency_list G,
  ranges::random_access_range Distances,
  ranges::random_access_range Predecessors,
- class WF = function<ranges::range_value_t<Distances>(edge_reference_t<G>)>,
+ class WF = std::function<ranges::range_value_t<Distances>(edge_reference_t<G>)>,
  class Visitor = dijkstra_visitor_base<G>,
  class Compare = less<ranges::range_value_t<Distances>>,
  class Combine = plus<ranges::range_value_t<Distances>>>
-requires is_arithmetic_v<ranges::range_value_t<Distances>> && //
+requires is_arithmetic_v<ranges::range_value_t<Distances>> && 
+ ranges::sized_range<Distances> && 
+ ranges::sized_range<Predecessors> && 
  convertible_to<vertex_id_t<G>, ranges::range_value_t<Predecessors>> &&
  basic_edge_weight_function<G, WF, ranges::range_value_t<Distances>, Compare, Combine> &&
  dijkstra_visitor<G, Visitor>
@@ -14,7 +16,7 @@ void dijkstra_shortest_paths(
  const vertex_id_t<G> source,
  Distances& distances,
  Predecessors& predecessor,
- WF&& weight  = [](edge_reference_t<G> uv) { return ranges::range_value_t<Distances>(1); },
+ WF&& weight = [](edge_reference_t<G> uv) { return ranges::range_value_t<Distances>(1); },
  Visitor&& visitor = dijkstra_visitor_base<G>(),
  Compare&& compare = less<ranges::range_value_t<Distances>>(),
  Combine&& combine = plus<ranges::range_value_t<Distances>>());

D3128_Algorithms/src/dijkstra_shortest_paths_multi.hpp

@@ -2,20 +2,23 @@ template <index_adjacency_list G,
  ranges::input_range Sources,
  ranges::random_access_range Distances,
  ranges::random_access_range Predecessors,
- class WF = function<ranges::range_value_t<Distances>(edge_reference_t<G>)>,
+ class WF = std::function<ranges::range_value_t<Distances>(edge_reference_t<G>)>,
  class Visitor = dijkstra_visitor_base<G>,
  class Compare = less<ranges::range_value_t<Distances>>,
  class Combine = plus<ranges::range_value_t<Distances>>>
-requires convertible_to<ranges::range_value_t<Sources>, vertex_id_t<G>> &&
- is_arithmetic_v<ranges::range_value_t<Distances>> &&
+requires convertible_to<ranges::range_value_t<Sources>, vertex_id_t<G>> && 
+ is_arithmetic_v<ranges::range_value_t<Distances>> && 
+ ranges::sized_range<Distances> && 
+ ranges::sized_range<Predecessors> && 
  convertible_to<vertex_id_t<G>, ranges::range_value_t<Predecessors>> &&
- basic_edge_weight_function<G, WF, ranges::range_value_t<Distances>, Compare, Combine>
+ basic_edge_weight_function<G, WF, ranges::range_value_t<Distances>, Compare, Combine> &&
+ dijkstra_visitor<G, Visitor>
 void dijkstra_shortest_paths(
  G& g,
  const Sources& sources,
  Distances& distances,
  Predecessors& predecessor,
- WF&& weight  = [](edge_reference_t<G> uv) { return ranges::range_value_t<Distances>(1); },
+ WF&& weight = [](edge_reference_t<G> uv) { return ranges::range_value_t<Distances>(1); },
  Visitor&& visitor = dijkstra_visitor_base<G>(),
  Compare&& compare = less<ranges::range_value_t<Distances>>(),
  Combine&& combine = plus<ranges::range_value_t<Distances>>());

D3128_Algorithms/src/find_negative_cycle.hpp

@@ -0,0 +1,6 @@
+template <index_adjacency_list G, ranges::forward_range Predecessors, class OutputIterator>
+requires output_iterator<OutputIterator, vertex_id_t<G>>
+void find_negative_cycle(G& g,
+ const Predecessors& predecessor,
+ const optional<vertex_id_t<G>>& cycle_vertex_id,
+ OutputIterator out_cycle);

D3128_Algorithms/src/shortest_paths_helpers.hpp

@@ -17,7 +17,5 @@ template <class Distances, class Predecessors>
 constexpr void init_shortest_paths(Distances& distances, Predecessors& predecessors) {
  // exposition only
  init_shortest_paths_distances(distances);
- size_t i = 0;
- for(auto& pred : predecessors)
- pred = i++; 
+ ranges::iota(predecessors, 0);
 }