Generating the Shortest Regex Dynamically from a source List of Strings

Question

I have a bunch of SKUs (stock keeping units) that represent a series of strings that I\'d like to create a single Regex to match for.

So, for example, if I have SKUs

Answer 1

This works if each SKU id have the same length.

// ...
string regexStr = Calculate(skus);
// ...

public static string Calculate(IEnumerable rest) {
    if (rest.First().Length > 0) {
        string[] groups = rest.GroupBy(r => r[0])
            .Select(g => g.Key + Calculate(g.Select(e => e.Substring(1))))
            .ToArray();
        return groups.Length > 1 ? "(" + string.Join("|", groups) + ")" : groups[0];
    } else {
        return string.Empty;
    }
}