在 VB.NET 中创建可搜索 "array" 的最有效方式

Most efficient way to create searchable "array" in VB.NET

我想创建一个VB.NET中的一些描述的多维数组,可以高效地存储和搜索以下数据(搜索第二个维度,return第一个)。

Folder Ext
excel xls
excel xlsx
word doc
word docx
powerpoint ppt
powerpoint pptx
Dim data As New Dictionary(Of String, String) From {
    {"xls",  "excel"},
    {"xlsx", "excel"},
    {"doc",  "word"},
    {"docx", "word"},
    {"ppt",  "powerpoint"},
    {"pptx", "powerpoint"}
}

像这样访问它:

Dim ext As String = "docx"
Dim folder As String = data(ext)