RosettaCodeData/Task/Quickselect-algorithm/AutoHotkey/quickselect-algorithm.ahk

40 lines
866 B
AutoHotkey

MyList := [9, 8, 7, 6, 5, 0, 1, 2, 3, 4]
Loop, 10
Out .= Select(MyList, 1, MyList.MaxIndex(), A_Index) (A_Index = MyList.MaxIndex() ? "" : ", ")
MsgBox, % Out
return
Partition(List, Left, Right, PivotIndex) {
PivotValue := List[PivotIndex]
, Swap(List, pivotIndex, Right)
, StoreIndex := Left
, i := Left - 1
Loop, % Right - Left
if (List[j := i + A_Index] <= PivotValue)
Swap(List, StoreIndex, j)
, StoreIndex++
Swap(List, Right, StoreIndex)
return StoreIndex
}
Select(List, Left, Right, n) {
if (Left = Right)
return List[Left]
Loop {
PivotIndex := (Left + Right) // 2
, PivotIndex := Partition(List, Left, Right, PivotIndex)
if (n = PivotIndex)
return List[n]
else if (n < PivotIndex)
Right := PivotIndex - 1
else
Left := PivotIndex + 1
}
}
Swap(List, i1, i2) {
t := List[i1]
, List[i1] := List[i2]
, List[i2] := t
}