microsoft-visualbasic-runtime/ComponentModel/Algorithm/DynamicProgramming/LongestCommonSubsequence.vb

128 lines
3.9 KiB
VB.net

#Region "Microsoft.VisualBasic::1dd182cc126f1ec9add3568244450e3c, Microsoft.VisualBasic.Core\ComponentModel\Algorithm\DynamicProgramming\LongestCommonSubsequence.vb"
' Author:
'
' asuka (amethyst.asuka@gcmodeller.org)
' xie (genetics@smrucc.org)
' xieguigang (xie.guigang@live.com)
'
' Copyright (c) 2018 GPL3 Licensed
'
'
' GNU GENERAL PUBLIC LICENSE (GPL3)
'
'
' This program is free software: you can redistribute it and/or modify
' it under the terms of the GNU General Public License as published by
' the Free Software Foundation, either version 3 of the License, or
' (at your option) any later version.
'
' This program is distributed in the hope that it will be useful,
' but WITHOUT ANY WARRANTY; without even the implied warranty of
' MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
' GNU General Public License for more details.
'
' You should have received a copy of the GNU General Public License
' along with this program. If not, see <http://www.gnu.org/licenses/>.
' /********************************************************************************/
' Summaries:
' Class LongestCommonSubsequence
'
' Properties: length, reversed, Sequence, si, ti
'
' Constructor: (+1 Overloads) Sub New
' Function: findMatch
'
'
' /********************************************************************************/
#End Region
Imports Microsoft.VisualBasic.Language.Python
Namespace ComponentModel.Algorithm.DynamicProgramming
''' <summary>
''' Longest Common Subsequence
''' </summary>
Public Class LongestCommonSubsequence(Of T)
Public Property length As Integer
Public Property si As Integer
Public Property ti As Integer
Public Property reversed As Boolean
Dim a As T()
Dim b As T()
Public ReadOnly Property Sequence() As T()
Get
If length >= 0 Then
Return a.slice(si, si + length)
Else
Return {}
End If
End Get
End Property
Sub New(s As T(), t As T(), equals As IEquals(Of T))
Dim mf = findMatch(s, t, equals)
Dim tr = t.slice(0).Reverse().ToArray
Dim mr = findMatch(s, tr, equals)
If (mf(0) >= mr(0)) Then
length = mf(0)
si = mf(1)
ti = mf(2)
reversed = False
Else
length = mr(0)
si = mr(1)
ti = t.Length - mr(2) - mr(0)
reversed = True
End If
End Sub
''' <summary>
'''
''' </summary>
''' <param name="s"></param>
''' <param name="t"></param>
''' <param name="equals"></param>
''' <returns>``{length, si, ti}``</returns>
Private Shared Function findMatch(s As T(), t As T(), equals As IEquals(Of T)) As Integer()
Dim m = s.Length
Dim n = t.Length
Dim match = {0, -1, -1}
Dim l = New Integer(m - 1)() {}
For i As Integer = 0 To m - 1
l(i) = New Integer(n - 1) {}
For j As Integer = 0 To n - 1
If equals(s(i), t(j)) Then
Dim v = If(i = 0 OrElse j = 0, 1, l(i - 1)(j - 1) + 1)
l(i)(j) = v
If (v > match.Length) Then
match(0) = v
match(1) = i - v + 1
match(2) = j - v + 1
End If
Else
l(i)(j) = 0
End If
Next
Next
Return match
End Function
End Class
End Namespace