[RESOLVED] Pascal's triangle

[Aash]

hi,
I've done many attempts but still didn't succeed in making a logic for pascal's triangle, I want you guys to get me start this task and I'll code it myself
looking at Paul's thread, I don't understand how did the Paul do it.
http://www.vbforums.com/showpost.php...23&postcount=4
So, i need a logic, how would i start it?


thanks

[bergerkiller]

Well if you look closely you can see the following:

1
12
123
1234
12345

So this is your base. On the other end you see that the inverted version of this is sticked to the one:

21
321
4321
54321

So it is somewhat like this:

1
left side add 2
right side add 2
left side add 3
right side add 3
Update number
left side add 4
right side add 4
left side add 5
right side add 5

Public Function addSides(ByVal input As String, ByVal text As String) As String
    Return StrReverse(text) & input & text
End Function

I only have no idea why his code is so long. Is something special supposed to happen? xD

EDIT

Note: you need some sort of special formatting before every line to center the 1 correctly.

[Aash]

I only have no idea why his code is so long. Is something special supposed to happen? xD

Yep. that confused me
ok, i got take a look at your explanation but in the figure:

sides of triangle would be 1, what about for numbers inside? (that's confusing for me)

i can understand that numbers adds up in a form of triangle and i can get a new number like: 1+1=2 then 1+2=3, 1+3=4 e.t.c
first i should make two right triangles and then concatenate them?




thanks..

[bergerkiller]

Neighbouring


Positions (array index):


Do as Paul did: start off with a 2-dimensional array of INTEGERs.

Dim Count As Integer = 5
Dim grid(Count - 1)(Count - 1) As Integer
Fill(grid, Count / 2, 0)

And make a recursive function fill this up.

Public Sub Fill(ByRef input()() As Integer, ByVal x As Integer, ByVal y As Integer)
   'check if input(x - 1, y - 1) is possible!!
   input(x, y) += input(x - 1, y - 1)
   'check if input(x + 1, y - 1) is possible!!
   input(x, y) += input(x + 1, y - 1)
   'neither? set 1
   if input(x, y) = 0 Then input(x, y) = 1

   'possible?
    Fill(input, x - 1, y + 1)
   'possible?
    Fill(input, x + 1, y + 1)
End Sub

[stanav]

Try this:

Private Function CreatePascalTriangle(ByVal numberOfRows As Integer) As List(Of Integer())
        Dim triangle As New List(Of Integer())
        For i As Integer = 0 To numberOfRows - 1
            triangle.Add(New Integer(i) {})
            triangle(i)(0) = 1
            triangle(i)(i) = 1
            If i > 1 Then
                For j As Integer = 1 To i - 1
                    triangle(i)(j) = triangle(i - 1)(j - 1) + triangle(i - 1)(j)
                Next
            End If
        Next
        Return triangle
    End Function
 
    Private Sub DisplayPascalTriangle(ByVal triangle As List(Of Integer()))
        Dim midpoint As Integer = triangle.Count
        Dim padding As Integer = 0
        Dim line As String = String.Empty
        Dim arr() As Integer = Nothing
        Dim sb As New System.Text.StringBuilder
        For row As Integer = 0 To triangle.Count - 1
            padding = midpoint - row
            arr = triangle(row)
            For i As Integer = 0 To arr.GetUpperBound(0)
                If i = 0 Then
                    line = arr(i).ToString.PadLeft(padding) & " "
                Else
                    line &= arr(i).ToString & " "
                End If
            Next
            sb.AppendLine(line)
        Next
        Debug.Write(sb.ToString)
    End Sub
 
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim triangle As List(Of Integer()) = CreatePascalTriangle(7)
        DisplayPascalTriangle(triangle)
    End Sub

[Aash]

will try it