Imports System
Public Class Program
Public Shared Sub PrintMatrixInSpiralForm(ByVal matrix As Integer()())
If matrix Is Nothing OrElse matrix.Length = 0 Then
Return
End If
Dim top As Integer = 0, bottom As Integer = matrix.Length - 1
Dim left As Integer = 0, right As Integer = matrix(0).Length - 1
While True
If left > right Then
Exit While
End If
For i As Integer = left To right
Console.Write(matrix(top)(i) & " ")
Next
Console.Write(Environment.NewLine)
top += 1
If top > bottom Then
Exit While
End If
For i As Integer = top To bottom
Console.Write(matrix(i)(right) & " ")
Next
Console.Write(Environment.NewLine)
right -= 1
If left > right Then
Exit While
End If
For i As Integer = right To left step -1
Console.Write(matrix(bottom)(i) & " ")
Next
Console.Write(Environment.NewLine)
bottom -= 1
If top > bottom Then
Exit While
End If
For i As Integer = bottom To top step -1
Console.Write(matrix(i)(left) & " ")
Next
Console.Write(Environment.NewLine)
left += 1
End While
End Sub
Public Shared Sub Main(ByVal args As String())
Dim matrix As Integer()() = New Integer()() {New Integer() {1, 2, 3, 4},
New Integer() {5, 6, 7, 8},
New Integer() {9, 10, 11, 12},
New Integer() {13, 14, 15, 16}}
PrintMatrixInSpiralForm(matrix)
End Sub
End Class
' run:
'
' 1 2 3 4
' 8 12 16
' 15 14 13
' 9 5
' 6 7
' 11
' 10
'
