28-12-2015 15:58:47 C# / Alogrithms 0 Bookmark(s) 196 View(s)

 

public static string GetLongestCommonSubstring(params string[] strings)
{
    var commonSubstrings = new HashSet<string>(strings[0].GetSubstrings());
    foreach (string str in strings.Skip(1))
    {
        commonSubstrings.IntersectWith(str.GetSubstrings());
        if (commonSubstrings.Count == 0)
            return string.Empty;
    }

    return commonSubstrings.OrderByDescending(s => s.Length).DefaultIfEmpty(string.Empty).First();
}

private static IEnumerable<string> GetSubstrings(this string str)
{
    for (int c = 0; c < str.Length - 1; c++)
    {
        for (int cc = 1; c + cc <= str.Length; cc++)
        {
            yield return str.Substring(c, cc);
        }
    }
}