关于Dijkstra算法的问题

Option Explicit

Private Sub Command1_Click()
    Dim a As Long, b As Long
    Dim w() As Long
    Dim tNum As Long
    Dim i As Long, j As Long
   
    tNum = 15
    '初始化权值,与自己的距离为0,若I与J不相邻为-1
    ReDim w(tNum - 1, tNum - 1)
    For i = 0 To tNum - 1
        For j = 0 To tNum - 1
            w(i, j) = IIf(i = j, 0, -1)
        Next
    Next
   
    '下面是手工添加的一些权值,方便测试假设各点间距离为都相同
   
    w(0, 1) = 1
    w(0, 2) = 1
    w(1, 2) = 1
    w(1, 4) = 1
    w(1, 0) = 1
    w(2, 0) = 1
    w(2, 1) = 1
    w(2, 4) = 1
    w(4, 1) = 1
    w(4, 2) = 1
    w(4, 3) = 1
    w(4, 7) = 1
    w(4, 8) = 1
    w(4, 11) = 1
    w(3, 4) = 1
    w(3, 5) = 1
    w(5, 3) = 1
    w(5, 7) = 1
    w(5, 6) = 1
    w(5, 12) = 1
    w(6, 5) = 1
    w(6, 7) = 1
    w(6, 9) = 1
    w(7, 4) = 1
    w(7, 5) = 1
    w(7, 6) = 1
    w(7, 9) = 1
    w(8, 4) = 1
    w(8, 9) = 1
    w(8, 10) = 1
    w(9, 8) = 1
    w(9, 7) = 1
    w(9, 6) = 1
    w(10, 8) = 1
    w(11, 4) = 1
    w(12, 5) = 1
    w(12, 13) = 1
    w(13, 12) = 1
    w(13, 14) = 1
    w(14, 13) = 1
   
    '下面调用显示结果
    a = 3
    b = 10
    Text1.Text = Dijkstra(a, b, tNum, w)                    '这里的结果是正常的3-->4-->8-->10
   
    '更换起点和终点
    a = 3
    b = 14
    Text2.Text = Dijkstra(a, b, tNum, w)                    '这里的结果是3-->14,明显不对,正常应该是3-->5-->12-->13-->14
   
End Sub


'改自网上的一个算法
Function Dijkstra(begin_p As Long, end_p As Long, pointNum As Long, w() As Long) As String
   
    Dim d() As Long
    Dim Bj() As Boolean
    Dim pre() As Long
   
    Dim i As Long
    Dim j As Long
    Dim n As Long
   
    n = pointNum - 1
   
    ReDim d(n)
    ReDim Bj(n)
    ReDim pre(n)
   
    For i = 0 To n
        d(i) = -1
    Next
   
    For i = 0 To n
        Bj(i) = False
    Next
   
    For i = 0 To n
        d(i) = w(begin_p, i)
        pre(i) = begin_p
    Next
   
    Dim dis As Long
    Dim p_num As Long
   
    Bj(begin_p) = True
   
    For i = 0 To n
      
        dis = -1
        p_num = -1
      
        For j = 0 To n
           
            If Not Bj(j) Then
                If (dis = -1) Or (d(j) > 0 And dis > d(j)) Then
                    dis = d(j)
                    p_num = j
                End If
            End If
        Next
      
      
        If p_num > 0 Then
           
            Bj(p_num) = True
           
            For j = 0 To n
               
                If w(p_num, j) > 0 And Not Bj(j) Then
                  
                    If (d(j) = -1) Or (d(j) > -1 And d(p_num) + w(p_num, j) < d(j)) Then
                        d(j) = d(p_num) + w(p_num, j)
                        pre(j) = p_num
                    End If
                End If
            Next
        Else
            Exit For
        End If
    Next
   
    Dim str As String
   
    i = end_p
    str = Trim(i)
    Do While (i <> begin_p)
        i = pre(i)
        str = Trim(i) & "-->" & str
    Loop
   
    Dijkstra = str
   
End Function