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Update how we use visited_trees in TreeSet #245

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Merged
gdalle merged 1 commit into from
Apr 10, 2025
Merged

Update how we use visited_trees in TreeSet #245

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27 changes: 6 additions & 21 deletions src/coloring.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -450,14 +450,9 @@ function TreeSet(
neighbor_position[k] = neighbor_position[k - 1] + 2 * tree_edge_indices[k]
end

# found_in_tree indicates if a given vertex is in each tree
found_in_tree = fill(false, nt)
# Record the most recent vertex from which each tree is visited
visited_trees = zeros(T, nt)

# Maintain a record of visited trees to efficiently reset found_in_tree
visited_trees = Vector{T}(undef, nt)

# Number of trees visited for each column of S
nt_visited = 0
rvS = rowvals(S)
for j in axes(S, 2)
for pos in nzrange(S, j)
Expand All @@ -474,13 +469,9 @@ function TreeSet(
# Position in tree_vertices where vertex j should be found or inserted
vertex_index = vertex_position[index_tree]

if !found_in_tree[index_tree]
# Mark that vertex j is present in the current tree
found_in_tree[index_tree] = true

# This is the first time an edge with vertex j has been found in the tree
nt_visited += 1
visited_trees[nt_visited] = index_tree
if visited_trees[index_tree] != j
# Mark the current tree as visited from vertex j
visited_trees[index_tree] = j

# Insert j into tree_vertices
vertex_position[index_tree] += 1
Expand All @@ -497,12 +488,6 @@ function TreeSet(
tree_neighbor_indices[vertex_index + 1] += 1
end
end

# Reset found_in_tree
for t in 1:nt_visited
found_in_tree[visited_trees[t]] = false
end
nt_visited = 0
end

# Compute a shifted cumulative sum of tree_edge_indices, starting from one
Expand All @@ -528,7 +513,7 @@ function TreeSet(

# Determine if each tree in the forest is a star
# In a star, at most one vertex has a degree strictly greater than one
is_star = found_in_tree
is_star = Vector{Bool}(undef, nt)

# Number of edges treated
num_edges_treated = zero(T)
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