Add Job Sequencing in Pascal (TheRenegadeCoder#4834)

Author: pascalecu

archive/p/pascal/job_sequencing.pas

@@ -0,0 +1,150 @@
+program JobSequencing;
+
+{$mode objfpc}{$H+}
+
+uses
+   Classes,
+   Generics.Collections,
+   Generics.Defaults,
+   Math,
+   StrUtils,
+   SysUtils;
+
+type
+   TJobInfo = record
+      JobId: integer;
+      Profit: integer;
+      Deadline: integer;
+   end;
+   TJobInfoList = specialize TList<TJobInfo>;
+   TIntegerList = specialize TList<integer>;
+
+procedure ShowUsage;
+begin
+   Writeln('Usage: please provide a list of profits and a list of deadlines');
+   Halt(1);
+end;
+
+function ParseIntegerList(const S: string): TIntegerList;
+var
+   Tokens: TStringArray;
+   Token: string;
+   Value: integer;
+begin
+   if S.Trim = '' then
+      ShowUsage;
+
+   Tokens := S.Split([',']);
+   if Length(Tokens) = 0 then
+      ShowUsage;
+
+   Result := TIntegerList.Create;
+   for Token in Tokens do
+   begin
+      if not TryStrToInt(Trim(Token), Value) then
+      begin
+         Result.Free;
+         ShowUsage;
+      end;
+      Result.Add(Value);
+   end;
+end;
+
+function CompareJobs(constref Left, Right: TJobInfo): integer;
+begin
+   // Compare profit descending
+   if Left.Profit > Right.Profit then
+      Exit(-1) // Left should come before Right
+   else if Left.Profit < Right.Profit then
+      Exit(1);
+
+   // If profit equal, compare deadline descending
+   if Left.Deadline > Right.Deadline then
+      Exit(-1)
+   else if Left.Deadline < Right.Deadline then
+      Exit(1);
+
+   Exit(0);
+end;
+
+
+function JobSequencing(const Profits, Deadlines: TIntegerList): integer;
+type
+   TJobComparer = specialize TComparer<TJobInfo>;
+   TBooleanArray = specialize TArray<boolean>;
+var
+   Jobs: TJobInfoList;
+   Job: TJobInfo;
+
+   Slots: TBooleanArray;
+
+   i, MaxDeadline: integer;
+   TotalProfit, SlotIndex: integer;
+begin
+   Jobs := TJobInfoList.Create;
+   try
+      // Build job list
+      Jobs.Capacity := Profits.Count;
+      for i := 0 to Profits.Count - 1 do
+      begin
+         Job.JobID := i + 1;
+         Job.Profit := Profits[i];
+         Job.Deadline := Deadlines[i];
+         Jobs.Add(Job);
+      end;
+
+      // Sort jobs by profit desc, deadline desc using a comparer
+      Jobs.Sort(TJobComparer.Construct(@CompareJobs));
+
+      // Find maximum deadline
+      MaxDeadline := MaxValue(Deadlines.ToArray);
+
+      // Initialize slots list with False (free)
+      SetLength(Slots, MaxDeadline);
+      for i := 0 to MaxDeadline - 1 do
+         Slots[i] := False;
+
+      TotalProfit := 0;
+      for Job in Jobs do
+      begin
+         // Find free slot at or before deadline
+         SlotIndex := Job.Deadline - 1;
+         while (SlotIndex >= 0) and Slots[SlotIndex] do
+            Dec(SlotIndex);
+
+         if SlotIndex >= 0 then
+         begin
+            Slots[SlotIndex] := True;
+            Inc(TotalProfit, Job.Profit);
+         end;
+      end;
+
+      Result := TotalProfit;
+
+   finally
+      Jobs.Free;
+   end;
+end;
+
+var
+   Profits, Deadlines: TIntegerList;
+
+begin
+   if ParamCount <> 2 then
+      ShowUsage;
+
+   Profits := nil;
+   Deadlines := nil;
+   try
+      Profits := ParseIntegerList(ParamStr(1));
+      Deadlines := ParseIntegerList(ParamStr(2));
+
+      if Profits.Count <> Deadlines.Count then
+         ShowUsage;
+
+      Writeln(JobSequencing(Profits, Deadlines));
+   finally
+      Profits.Free;
+      Deadlines.Free;
+   end;
+end.