Imports System
Public Class MaxProductOfSubarray_CSharp
Public Shared Function getMaxProductOfSubarray(ByVal arr As Integer()) As Integer
Dim len As Integer = arr.Length
If len = 0 Then
Return 0
End If
Dim max_current_index As Integer = arr(0), min_current_index As Integer = arr(0), max_product As Integer = arr(0)
Console.Write("arr[i] = {0:D} max_current_index = {1:D} min_current_index = {2:D} max_product = {3:D}" & Environment.NewLine, arr(0), max_current_index, min_current_index, max_product)
For i As Integer = 1 To len - 1
Dim temp As Integer = max_current_index
max_current_index = Math.Max(arr(i), Math.Max(arr(i) * max_current_index, arr(i) * min_current_index))
min_current_index = Math.Min(arr(i), Math.Min(arr(i) * temp, arr(i) * min_current_index))
Console.Write("arr[i] = {0:D} max_current_index = {1:D} min_current_index = {2:D}" & Environment.NewLine, arr(i), max_current_index, min_current_index)
max_product = Math.Max(max_product, max_current_index)
Console.Write("max_product = {0:D}" & Environment.NewLine, max_product)
Next
Return max_product
End Function
Public Shared Sub Main(ByVal args As String())
Dim arr As Integer() = New Integer() {-4, 8, 2, 5, 90, 7, 0, -3, 6} ' 8 * 2 * 5 * 90 * 7 = 50400
Console.Write("maximum product = " & getMaxProductOfSubarray(arr))
End Sub
End Class
' run:
'
' arr[i] = -4 max_current_index = -4 min_current_index = -4 max_product = -4
' arr[i] = 8 max_current_index = 8 min_current_index = -32
' max_product = 8
' arr[i] = 2 max_current_index = 16 min_current_index = -64
' max_product = 16
' arr[i] = 5 max_current_index = 80 min_current_index = -320
' max_product = 80
' arr[i] = 90 max_current_index = 7200 min_current_index = -28800
' max_product = 7200
' arr[i] = 7 max_current_index = 50400 min_current_index = -201600
' max_product = 50400
' arr[i] = 0 max_current_index = 0 min_current_index = 0
' max_product = 50400
' arr[i] = -3 max_current_index = 0 min_current_index = -3
' max_product = 50400
' arr[i] = 6 max_current_index = 6 min_current_index = -18
' max_product = 50400
' maximum product = 50400
'
