Initial data commit

Task/Dijkstras-algorithm/11l/dijkstras-algorithm.11l

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+T Edge
+   String start
+   String end
+   Int cost
+
+   F (start, end, cost)
+      .start = start
+      .end = end
+      .cost = cost
+
+T Graph
+   [Edge] edges
+   Set[String] vertices
+
+   F (edges)
+      .edges = edges.map((s, e, c) -> Edge(s, e, c))
+      .vertices = Set(.edges.map(e -> e.start)).union(Set(.edges.map(e -> e.end)))
+
+   F dijkstra(source, dest)
+      assert(source C .vertices)
+      V dist = Dict(.vertices, vertex -> (vertex, Float.infinity))
+      V previous = Dict(.vertices, vertex -> (vertex, ‘’))
+      dist[source] = 0
+      V q = copy(.vertices)
+      V neighbours = Dict(.vertices, vertex -> (vertex, [(String, Int)]()))
+      L(start, end, cost) .edges
+         neighbours[start].append((end, cost))
+
+      L !q.empty
+         V u = min(q, key' vertex -> @dist[vertex])
+         q.remove(u)
+         I dist[u] == Float.infinity | u == dest
+            L.break
+         L(v, cost) neighbours[u]
+            V alt = dist[u] + cost
+            I alt < dist[v]
+               dist[v] = alt
+               previous[v] = u
+
+      Deque[String] s
+      V u = dest
+      L previous[u] != ‘’
+         s.append_left(u)
+         u = previous[u]
+      s.append_left(u)
+      R s
+
+V graph = Graph([(‘a’, ‘b’, 7),  (‘a’, ‘c’, 9),  (‘a’, ‘f’, 14), (‘b’, ‘c’, 10),
+                 (‘b’, ‘d’, 15), (‘c’, ‘d’, 11), (‘c’, ‘f’, 2),  (‘d’, ‘e’, 6),
+                 (‘e’, ‘f’, 9)])
+print(graph.dijkstra(‘a’, ‘e’))