Три максимума и пять минимумов

var a:=ArrRandom(100, -10000, 10000);

var d:=new SortedDictionary<integer, integer>;
foreach var x in a do d[x]:=d.Get(x)+1;

##
var a:=ArrRandom(100, -10000, 10000);
var b := a.Sorted.Distinct.ToArray;
Print(b[:5] + b[^3:])

##
var a:=ArrRandom(100, -10000, 10000);
var tmp:= a.Order; //a.Sorted
var max3:=tmp.TakeLast(3).reverse.println;
var min5:=tmp.Take(5).println;

##
var a := ArrRandom(1_000_000, -10_000, 10_000);
var sw := new StopWatch;
sw.Start;
 
var b := a.Sorted.Distinct.ToArray;
var r := b[:5] + b[^3:];
 
sw.Stop;
PrintLn(r);
PrintLn(sw.Elapsed);

##
  var a := ArrRandom(1000000, -10000, 10000);
  var sw := new StopWatch;
  sw.Start;
 
  var b := |a[0]|;
  var k := 1;
  repeat
    if b.FindIndex(x -> x = a[k]) < 0 then b := b + |a[k]|;
    inc(k)
  until length(b) = 5;
  var c := b[:3];
  for var i := k to High(a) do
    if (b.FindIndex(x -> x = a[i]) < 0) and (b[b.IndexMax] > a[i]) then b[b.IndexMax] := a[i]
    else
      if (c.FindIndex(x -> x = a[i]) < 0) and (c[c.IndexMin] < a[i]) then c[c.Indexmin] := a[i];
  var r := (b + c).Sorted;
 
  sw.Stop;
  Println(r);
  Println(sw.Elapsed)

procedure TestMinMax;
type
  THelper = specialize TGOrdinalArrayHelper<Integer>;
 
var
  MinList: array of Integer = nil;
  MaxList: array of Integer = nil;
  MinHi: Integer = -1;
  MaxHi: Integer = -1;
 
  procedure AddMin(Value: Integer); inline;
  var
    I: Integer;
  begin
    if Value < MinList[MinHi] then
      for I := 0 to MinHi do
        if Value <= MinList[I] then begin
          MinList[I] := Value; break;
        end;
  end;
 
  procedure AddMax(Value: Integer); inline;
  var
    I: Integer;
  begin
    if Value > MaxList[0] then
      for I := MaxHi downto 0 do
        if Value >= MaxList[I] then begin
          MaxList[I] := Value; break;
        end;
  end;
 
var
  Data, r: array of Integer;
  I: Integer;
  Timer: TStopWatch;
const
  RangeLo  = -10000;
  RangeHi  = 10000;
  DataSize = 1000000;
  MaxCount = 3;
  MinCount = 5;
begin
  Data := THelper.CreateRandomInRange(DataSize, RangeLo, RangeHi);
  Timer := TStopWatch.StartNew;
  MinList := Copy(Data, 0, MinCount);
  MaxList := Copy(Data, 0, MaxCount);
  THelper.Sort(MinList);
  THelper.Sort(MaxList);
  MinHi := High(MinList);
  MaxHi := High(MaxList);
  for I := Succ(Min(MaxCount, MinCount)) to High(Data) do begin
    AddMin(Data[I]);
    AddMax(Data[I]);
  end;
  r := MinList + MaxList;
  Timer.Stop;
  WriteLn(Stringify(TypeInfo(r), r));
  WriteLn(Timer.ElapsedMilliseconds.ToString);
end;

const mnSize=5; mxSize=3;
var
  mn: array [0..mnSize-1] of Integer;
  mx: array [0..mxSize-1] of Integer;
  mnCnt, mxCnt: Integer;
 
begin
  var a := ArrRandom(1_000_000, -10_000, 10_000);
  // First
  var sw1:=new StopWatch; sw1.Start;
  var b := a.Sorted.Distinct.ToArray;
  var r := b[:5] + b[^3:];
  sw1.Stop; PrintLn(r, sw1.Elapsed);
  
  // Second
  var sw2:=new StopWatch; sw2.Start;
  for var k:=0 to Length(a)-1 do begin
    var i: Integer;
    var t:=a[k];
    i:=mnCnt; while (i>0) and (mn[i-1]>t) do Dec(i);
    if i<mnSize then if (i=0) or (mn[i-1]<>t) then begin
      Inc(mnCnt,Ord(mnCnt<mnSize));
      for var j:=mnCnt-1 downto i+1 do mn[j]:=mn[j-1]; mn[i]:=t;
    end;
    i:=mxCnt; while (i>0) and (mx[i-1]<t) do Dec(i);
    if i<mxSize then if (i=0) or (mx[i-1]<>t) then begin
      Inc(mxCnt,Ord(mxCnt<mxSize));
      for var j:=mxCnt-1 downto i+1 do mx[j]:=mx[j-1]; mx[i]:=t;
    end;
  end;
  sw2.Stop; PrintLn(mn, mx, sw2.Elapsed);
end.