Type Tupla
    Prioridad As Integer
    Tarea As String
End Type
Dim Shared As Tupla a()
Dim Shared As Integer n 'número de eltos. en la matriz, el último elto. es n-1

Function Izda(i As Integer) As Integer
    Izda = 2 * i + 1
End Function

Function Dcha(i As Integer) As Integer
    Dcha = 2 * i + 2
End Function

Function Parent(i As Integer) As Integer
    Parent = (i - 1) \ 2
End Function

Sub Intercambio(i As Integer, j As Integer)
    Dim t As Tupla
    t = a(i)
    a(i) = a(j)
    a(j) = t
End Sub

Sub bubbleUp(i As Integer)
    Dim As Integer p = Parent(i)
    Do While i > 0 And a(i).Prioridad < a(p).Prioridad
        Intercambio i, p
        i = p
        p = Parent(i)
    Loop
End Sub

Sub Annadir(fPrioridad As Integer, fTarea As String)
    n += 1
    If n > Ubound(a) Then Redim Preserve a(2 * n)
    a(n - 1).Prioridad = fPrioridad
    a(n - 1).Tarea = fTarea
    bubbleUp (n - 1)
End Sub

Sub trickleDown(i As Integer)
    Dim As Integer j, l, r
    Do
        j = -1
        r = Dcha(i)
        If r < n And a(r).Prioridad < a(i).Prioridad Then
            l = Izda(i)
            If a(l).Prioridad < a(r).Prioridad Then
                j = l
            Else
                j = r
            End If
        Else
            l = Izda(i)
            If l < n And a(l).Prioridad < a(i).Prioridad Then j = l
        End If
        If j >= 0 Then Intercambio i, j
        i = j
    Loop While i >= 0
End Sub

Function Remove() As Tupla
    Dim As Tupla x = a(0)
    a(0) = a(n - 1)
    n = n - 1
    trickleDown 0
    If 3 * n < Ubound(a) Then Redim Preserve a(Ubound(a) \ 2)
    Remove = x
End Function


Redim a(4)
Annadir (3, "Clear drains")
Annadir (4, "Feed cat")
Annadir (5, "Make tea")
Annadir (1, "Solve RC tasks")
Annadir (2, "Tax return")
Dim t As Tupla
Do While n > 0
    t = Remove
    Print t.Prioridad; "  "; t.Tarea
Loop
Sleep