Data update

Task/Knapsack-problem-Bounded/Lua/knapsack-problem-bounded.lua

@@ -0,0 +1,180 @@
+#!/usr/bin/env  lua
+
+--- knapsack packing for max value under wieght limit
+
+ -- A: use value/weight score as pre-sort
+ -- B: initial run with no items excluded
+ -- C: try combos excluding each item for best value
+
+
+--- table of tables
+-- {name                  weight  value quantity   wt/val }
+items =  {
+   {"map",                 9,  150,  1},
+   {"compass",		      13,   35,	 1},
+   {"water",		     153,  200,  2},
+   {"sandwich",		      50,   60,	 2},
+   {"glucose",		      15,   60,	 2},
+   {"tin",		          68,   45,	 3},
+   {"banana",		      27,   60,	 3},
+   {"apple",		      39,   40,	 3},
+   {"cheese",		      23,   30,	 1},
+   {"beer",		          52,   10,	 3},
+   {"suntan cream",	      11,   70,	 1},
+   {"camera",		      32,   30,	 1},
+   {"t-shirt",		      24,   15,	 2},
+   {"trousers",		      48,   10,	 2},
+   {"umbrella",		      73,   40,	 1},
+   {"waterproof trousers",    42,   70,	 1},
+   {"waterproof overclothes", 43,   75,	 1},
+   {"note-case",	      22,   80,  1},
+   {"sunglasses",	       7,   20,  1},
+   {"towel",		      18,   12,	 2},
+   {"socks",		       4,   50,	 1},
+   {"book",		          30,   10,	 2},
+}
+
+-- for output
+function print_as_sack(its)
+   if its == nil then return end
+
+   -- format columns
+   -- [20                  |8     |8     |8     ]
+   local head_fmt = "%-20s\t%-8s\t%-8s\t%-8s"
+   local data_fmt = "%-20s\t%-8d\t%-8d\t%-8d"
+
+   local head_table =
+      string.format(head_fmt, "item", "weight", "value", "quantity")
+
+   io.write(head_table, "\n")
+   line = string.rep("-" , 64)
+   io.write(line, "\n")
+
+   for n=1,#its do
+      it = its[n]
+      local name,wt,val,q = table.unpack(it)
+
+      local fmt_table =
+	 string.format(data_fmt, name, wt, val, q)
+      io.write(fmt_table, "\n")
+   end
+   io.write(line, "\n")
+end
+
+-- calc value:weight ratio
+function append_wv (its)
+
+   for index, it in pairs(its) do
+      local name,wt,val,q = table.unpack(it)
+      wv  =  val / wt
+      it[#it+1] = wv -- append
+   end
+end
+
+-- sort by 5th item of each table entry
+function sort_by_wv (its)
+   -- sorts decreasing
+   local wv_sorter = function(a,b) return a[5] > b[5] end
+   table.sort(its, wv_sorter)
+end
+
+-- pack sorted by v:w ratio
+-- all or none per item
+function add_up (its, max, excl)
+
+   local sack_items = {}
+   local sack = {}
+   local this_weight = 0
+   local this_value  = 0
+
+   for i = 1,#its do
+      it = its[i]
+
+      -- is same table?
+      --    lua has no continue keyword
+      if it == excl then goto continue end
+
+      -- unpack into vars
+      local name,wt,val,q,wv = table.unpack(it)
+      local count  = 0
+      local w      = 0
+      for j = 1, q do
+	     local t_wt = wt +this_weight
+	     if t_wt < max then
+	        this_value  = this_value + val
+	        this_weight = t_wt
+	        count = count + 1
+	     end
+      end
+
+      if this_weight >= max then break end
+
+      if count > 0 then
+	     _s = {name, count}
+	     table.insert (sack, _s)
+      end
+
+      ::continue::  --skip item, continue
+   end  -- for items
+
+   -- go through chosen sack
+   -- make sack of items
+      for s = 1,#sack do
+	     local s_item  = sack[s]
+	     local s_name,s_count = table.unpack(s_item)
+
+   	     for j = 1,#its do	
+	        local it = its[j]
+	        local iname = it[1]
+	        if iname == s_name then
+	           it[4] = s_count
+	           table.insert(sack_items, it)
+	        end -- if
+	     end -- for j
+     end -- for sack
+
+      -- update best
+      if this_value > best_value then
+	     best_value = this_value
+	     best_weight = this_weight
+	     best_sack = sack_items
+      end
+end  -- function add_up
+
+-- Main execution
+if debug.getinfo(1).what == "main" then
+
+   max_weight = 400
+   best_weight = 0
+   best_value  = 0
+   best_sack = {}
+
+   start = os.clock()
+
+   append_wv(items)   -- add weight/value
+
+   sort_by_wv(items)  -- sort by wv
+
+   add_up(items, max_weight, {}) -- first try
+
+   -- with each item excluded
+   for i = 1, #items do
+      add_up(items, max_weight, items[i])
+   end
+
+   stop = os.clock()
+
+   time = stop - start     -- seconds
+
+   usec_time = time * 1e6 --microseconds
+
+
+   -- output
+   print_as_sack(best_sack)
+   print ("value:\t", best_value)
+   print("weight:\t", best_weight)
+   print("time:\t" , usec_time , " usec")
+
+   os.exit(0)
+end
+-- end