Initial data commit

Task/Dijkstras-algorithm/J/dijkstras-algorithm-2.j

@@ -0,0 +1,43 @@
+vertices=: ;:'a b c d e f'
+edges=:|: ;:;._2]0 :0
+  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
+)
+
+shortest_path=:1 :0
+:
+  NB. x: path endpoints, m: vertex labels, y: edges (starts,ends,:costs)
+  terminals=. m i. x
+  starts=. m i. 0{y
+  ends=.   m i. 1{y
+  tolls=.  _&".@> 2{y
+  C=. tolls (starts,&.>ends)}_$~2##m
+  bestprice=. (<terminals){ (<. <./ .+/~)^:_ C
+  best=. i.0
+  if. _>bestprice do.
+    paths=. ,.{.terminals
+    goal=. {:terminals
+    costs=. ,0
+    while. #costs do.
+      next=. ({:paths){C
+      keep=. (_>next)*bestprice>:next+costs
+      rep=. +/"1 keep
+      paths=. (rep#"1 paths),(#m)|I.,keep
+      costs=. (rep#"1 costs)+keep #&, next
+      if. #j=. I. goal = {:paths do.
+        best=. best, (bestprice=j{costs)# <"1 j{|:paths
+      end.
+      toss=. <<<j,I.bestprice<:costs
+      paths=. toss {"1 paths
+      costs=. toss { costs
+    end.
+  end.
+  best {L:0 _ m
+)