Data commit

Task/Priority-queue/Pascal/priority-queue-4.pas

@@ -0,0 +1,47 @@
+program PqDemo;
+{$mode delphi}
+uses
+  SysUtils, PQueue;
+
+type
+  TTask = record
+    Name: string; Prio: Integer;
+  end;
+
+const
+  Tasks: array of TTask = [
+    (Name: 'Clear drains';   Prio: 3), (Name: 'Feed cat';       Prio: 4),
+    (Name: 'Make tea';       Prio: 5), (Name: 'Solve RC tasks'; Prio: 1),
+    (Name: 'Tax return';     Prio: 2)];
+
+function TaskCmp(const L, R: TTask): Boolean;
+begin
+  Result := L.Prio < R.Prio;
+end;
+
+var
+  q: TPriorityQueue<TTask>;
+  h: q.THandle = q.NULL_HANDLE;
+  t: TTask;
+  MaxPrio: Integer = Low(Integer);
+begin
+  Randomize;
+  q := TPriorityQueue<TTask>.Create(@TaskCmp);
+  for t in Tasks do begin
+    if t.Prio > MaxPrio then MaxPrio := t.Prio;
+    if Pos('cat', t.Name) > 0 then
+      h := q.Push(t)
+    else
+      q.Push(t);
+  end;
+  if (h <> q.NULL_HANDLE) and Boolean(Random(2)) then begin
+    WriteLn('Cat is angry!');
+    t := q.GetValue(h);
+    t.Prio := Succ(MaxPrio);
+    q.Update(h, t);
+  end;
+  WriteLn('Task list:');
+  while q.TryPop(t) do
+    WriteLn('  ', t.Prio, ' ', t.Name);
+  q.Free;
+end.