More efficient reset of visited vertices in order.jl

Author: amontoison

src/order.jl

@@ -366,20 +366,24 @@ function vertices(
     n = nb_vertices(g, Val(side))
     degrees_dist2 = zeros(T, n)
     visited = fill(false, n)
+    vertices_visited = zeros(T, n-1)
+    num_visited = zero(T)
     for v in vertices(g, Val(side))
         for w1 in neighbors(g, Val(side), v)
             for w2 in neighbors(g, Val(other_side), w1)
                 if w2 != v && !visited[w2]
                     degrees_dist2[v] += 1
                     visited[w2] = true
+                    num_visited += 1
+                    vertices_visited[num_visited] = w2
                 end
             end
         end
-        for w1 in neighbors(g, Val(side), v)
-            for w2 in neighbors(g, Val(other_side), w1)
-                visited[w2] = false
-            end
+        for k in 1:num_visited
+            z = vertices_visited[k]
+            visited[z] = false
         end
+        num_visited = 0
     end
     if degree_increasing(; degtype, direction)
         degrees = zeros(T, n)
@@ -390,26 +394,25 @@ function vertices(
     db = DegreeBuckets(T, degrees, maxd2; reproduce_colpack=order.reproduce_colpack)
     π = T[]
     sizehint!(π, n)
-    fill!(visited, false)
     for _ in 1:nb_vertices(g, Val(side))
         u = pop_next_candidate!(db; direction)
         direction == :low2high ? push!(π, u) : pushfirst!(π, u)
         for w in neighbors(g, Val(side), u)
             for v in neighbors(g, Val(other_side), w)
-                if v == u || visited[v]
-                    continue
-                else
+                if v != u && !visited[v]
                     visited[v] = true
+                    num_visited += 1
+                    vertices_visited[num_visited] = v
                 end
                 already_ordered(db, v) && continue
                 update_bucket!(db, v; degtype, direction)
             end
         end
-        for w in neighbors(g, Val(side), u)
-            for v in neighbors(g, Val(other_side), w)
-                visited[v] = false  # reset only the toggled ones to false
-            end
+        for k in 1:num_visited
+            z = vertices_visited[k]
+            visited[z] = false
         end
+        num_visited = 0
     end
     return π
 end