Dijkstra's Algorithm in Ruby

dijkstra.rb

# From http://www.algolist.com/code/java/Dijkstra%27s_algorithm
# Here you can find the algorithm in Java, C, C++, Python, Ruby and PHP.
#
# You need pqueue: gem install pqueue
#
require 'pqueue'

class Algorithm

  INFINITY = 1 << 32

  def self.dijkstra(source, edges, weights, n)
    visited = Array.new(n, false)
    shortest_distances = Array.new(n, INFINITY)
    previous = Array.new(n, nil)
    pq = PQueue.new(proc {|x,y| shortest_distances[x] < shortest_distances[y]})
  
    pq.push(source)
    visited = true
    shortest_distances = 0
  
    while pq.size != 0
      v = pq.pop
      visited[v] = true
      if edges[v]
        edges[v].each do |w|
          if !visited[w] and shortest_distances[w] > shortest_distances[v] + weights[v][w]
            shortest_distances[w] = shortest_distances[v] + weights[v][w]
            previous[w] = v
            pq.push(w)
          end
        end
      end
    end
  return [shortest_distances, previous]
  end
end