Imports System
Imports System.Collections.Generic
Class LongestConsecutiveSequence
Public Shared Function LongestConsecutive(ByVal nums As Integer()) As Integer
Dim numSet As HashSet(Of Integer) = New HashSet(Of Integer)(nums)
Dim longestStreak As Integer = 0
For Each num As Integer In numSet
If Not numSet.Contains(num - 1) Then
Dim currentNum As Integer = num
Dim currentStreak As Integer = 1
While numSet.Contains(currentNum + 1)
currentNum += 1
currentStreak += 1
End While
longestStreak = Math.Max(longestStreak, currentStreak)
End If
Next
Return longestStreak
End Function
Public Shared Sub Main()
Dim nums As Integer() = {680, 4, 590, 3, 2, 1}
Dim result As Integer = LongestConsecutive(nums)
Console.WriteLine("Length of the longest consecutive sequence: " & result)
End Sub
End Class
' run:
'
' Length of the longest consecutive sequence: 4
'
