Data commit

Task/Priority-queue/Pascal/priority-queue-1.pas

@@ -0,0 +1,74 @@
+program PriorityQueueTest;
+
+uses Classes;
+
+Type
+ TItem = record
+    Priority:Integer;
+    Value:string;
+ end;
+
+ PItem = ^TItem;
+
+TPriorityQueue = class(Tlist)
+ procedure Push(Priority:Integer;Value:string);
+ procedure SortPriority();
+ function Pop():String;
+ function Empty:Boolean;
+end;
+
+{ TPriorityQueue }
+
+procedure TPriorityQueue.Push(Priority:Integer;Value:string);
+var
+ Item: PItem;
+begin
+    new(Item);
+    Item^.Priority := Priority;
+    Item^.Value := Value;
+    inherited Add(Item);
+    SortPriority();
+end;
+
+procedure TPriorityQueue.SortPriority();
+var
+ i,j:Integer;
+begin
+ if(Count < 2) Then  Exit();
+
+ for i:= 0 to Count-2 do
+  for j:= i+1 to Count-1 do
+    if ( PItem(Items[i])^.Priority > PItem(Items[j])^.Priority)then
+      Exchange(i,j);
+end;
+
+function TPriorityQueue.Pop():String;
+begin
+ if count = 0  then
+   Exit('');
+ result := PItem(First)^.value;
+ Dispose(PItem(First));
+ Delete(0);
+end;
+
+function TPriorityQueue.Empty:Boolean;
+begin
+ Result := Count = 0;
+end;
+
+var
+ Queue : TPriorityQueue;
+begin
+  Queue:= TPriorityQueue.Create();
+
+  Queue.Push(3,'Clear drains');
+  Queue.Push(4,'Feed cat');
+  Queue.Push(5,'Make tea');
+  Queue.Push(1,'Solve RC tasks');
+  Queue.Push(2,'Tax return');
+
+  while not Queue.Empty() do
+   writeln(Queue.Pop());
+
+  Queue.free;
+end.