dijkstra in lua

dijkstra.lua

require('dumper')
function dump(...)
   print( DataDumper(...), "\n---")
end

path = { {},{},{},{},{},{}}
dpath = {}
dpath[1] = { {2, 5}, { 6, 4}, {5,2} }
dpath[2] = { {3, 6}, {6, 2}, }
dpath[3] = { {4, 4} }
dpath[4] = { {6,2 }, {5, 6}}
dpath[5] = { {6,3} }
dpath[6] = {}
path_size = 6

-- Setting a Start and Goal Flag                                                                                                                                                                                                                                      
START = 1
GOAL = 3
for i,v in ipairs(dpath)
do
   for j, val in ipairs(v)
   do
      idx, cost = val[1], val[2]
      table.insert( path[idx], {i,cost} )
   end
end
for i,v in ipairs(path) do
   for j, v2 in ipairs(v) do
      table.insert(dpath[i], v2)
   end
end
-- http://www.deqnotes.net/acmicpc/dijkstra/                                                                                                                                                                                                                          
fixed = {}
updated = {}
undefined = 10000000
for i = 1, path_size do
   fixed[i] = false
   updated[i] = undefined
end
fixed[START] = false
updated[START] = 0
update = false
while (true) do
   min = 10000
   fidx, ncost = -1, 10000
   for afix, acost in ipairs(updated) do
      if fixed[afix] == false and acost ~= undefined and ncost > acost then
         ncost = acost
         fidx = afix
         update = true
      end
   end
   if not update then break end
   fixed[fidx] = true
   if fidx == GOAL then
      print("GOAL: cost", updated[GOAL] )
      break
   end
   acost = updated[fidx]
   update = false
   for from, v in ipairs(dpath) do
      if from == fidx then
      for no, v2 in ipairs(v) do
         to, tocost = v2[1], v2[2]
         if updated[to] > acost + tocost then
            updated[to] = acost + tocost
            update = true
         end
      end
      end
   end
   if not update then
      break
   end
end

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