September 2017 Update

Task/Knapsack-problem-0-1/Pascal/knapsack-problem-0-1.pascal

@@ -0,0 +1,83 @@
+program project1;
+uses
+  sysutils, classes, math;
+
+const
+  MaxWeight = 400;
+  N = 21;
+
+type
+  TMaxArray = array[0..N, 0..MaxWeight] of integer;
+
+  TEquipment = record
+    Description : string;
+    Weight : integer;
+    Value : integer;
+  end;
+
+  TEquipmentList = array[1..N] of TEquipment;
+
+var
+   M:TMaxArray;
+   MaxValue, WeightLeft, i, j, Sum : integer;
+   S,KnapSack:TStringList;
+   L:string;
+   List:TEquipmentList;
+
+begin
+   //Put all the items into an array called List
+   L:='map ,9 ,150,compass ,13 ,35 ,water ,153 ,200 ,sandwich,50 ,160 ,glucose ,15 ,60 ,tin,68 ,45 ,banana,27,60 ,apple ,39 ,40 ,cheese ,23 ,30 ,beer ,52 ,10 ,suntancreme ,11 ,70 ,camera ,32 ,30 ,T-shirt ,24 ,15 ,trousers ,48 ,40 ,waterprooftrousers ,42 ,70 ,waterproofoverclothes ,43 ,75 ,notecase ,22 ,80 ,sunglasses ,7 ,20 ,towel ,18 ,12 ,socks ,4 ,50 ,book ,30 ,10';
+   S:=TStringList.create;
+   S.Commatext:=L;
+
+   For i:= 1 to N do
+   begin
+      List[i].Description:=S[3*i - 3];
+      List[i].Weight:=strtoint(S[3*i - 2]);
+      List[i].Value:=strtoint(S[3*i - 1]);
+   end;
+
+   //create M, a table linking the possible items for each weight
+   //and recording the value at that point
+   for j := 0 to MaxWeight do
+       M[0, j] := 0
+
+   for i := 1 to N do
+       for j := 0 to MaxWeight do
+           if List[i].weight > j then
+               M[i, j] := M[i-1, j]
+           else
+               M[i, j] := max(M[i-1, j], M[i-1, j-List[i].weight] + List[i].value);
+
+   //get the highest total value by testing every value in table M
+   for i:=1 to N do
+       for j:= 0 to MaxWeight do
+           If M[i,j] > MaxValue then
+               MaxValue := m[i,j];
+
+   writeln('Highest total value : ',MaxValue);
+
+  //Work backwards through the items to find those items that go in the Knapsack (a stringlist)
+   KnapSack := TStringList.create;
+   WeightLeft := MaxWeight;
+   For i:= N downto 1 do
+       if M[i,WeightLeft] = MaxValue then
+          if M[i-1, WeightLeft - List[i].Weight] = MaxValue - List[i].Value then
+          begin
+            Knapsack.add(List[i].Description + ' ' + IntToStr(List[i].Weight)+ ' ' + inttostr(List[i].Value));
+            MaxValue := MaxValue - List[i].Value;
+            WeightLeft := WeightLeft - List[i].Weight;
+          end
+
+   //Show the items in the knapsack
+   writeln('Number of items     : ',KnapSack.count);
+   writeln('-------------------------');
+   For i:= KnapSack.count-1 downto 0 do
+     writeln(KnapSack[i]);
+
+   KnapSack.free;
+   S.free;
+   writeln('-------------------------');
+   writeln('done');
+   readln;
+end.