此扩展名找到最长，最常见的子字符串。请注意，
"1"每个字符串中包含的频率也比更高
"10"。（仅C＃）：
public static class StringExtensions{ public static IEnumerable<string> GetMostCommonSubstrings(this IList<string> strings) { if (strings == null) throw new ArgumentNullException("strings"); if (!strings.Any() || strings.Any(s => string.IsNullOrEmpty(s))) throw new ArgumentException("None string must be empty", "strings"); var allSubstrings = new List<List<string>>(); for (int i = 0; i < strings.Count; i++) { var substrings = new List<string>(); string str = strings[i]; for (int c = 0; c < str.Length - 1; c++) { for (int cc = 1; c + cc <= str.Length; cc++) { string substr = str.Substring(c, cc); if (allSubstrings.Count < 1 || allSubstrings.Last().Contains(substr)) substrings.Add(substr); } } allSubstrings.Add(substrings); } if (allSubstrings.Last().Any()) { var mostCommon = allSubstrings.Last() .GroupBy(str => str) .OrderByDescending(g => g.Key.Length) .ThenByDescending(g => g.Count()) .Select(g => g.Key); return mostCommon; } return Enumerable.Empty<string>(); }}现在很简单：
string[] x = new[] { "10111", "10122", "10250", "10113" };string mostCommonSubstring = x.GetMostCommonSubstrings().FirstOrDefault();if (mostCommonSubstring != null){ for (int i = 0; i < x.Length; i++) x[i] = x[i].Replace(mostCommonSubstring, "");}Console.Write(string.Join(", ", x));输出：
111, 122, 250, 113
[**DEMO**](http://ideone.com/dCBAir)
编辑
：如果只想找到最长的公共子串而不考虑出现的频率，则可以使用以下优化方法（O（n）操作）
HashSet<string>：
public static string GetLongestCommonSubstring(this IList<string> strings){ if (strings == null) throw new ArgumentNullException("strings"); if (!strings.Any() || strings.Any(s => string.IsNullOrEmpty(s))) throw new ArgumentException("None string must be empty", "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 null; } return commonSubstrings.OrderByDescending(s => s.Length).First();}public static IEnumerable<string> GetSubstrings(this string str){ if (string.IsNullOrEmpty(str)) throw new ArgumentException("str must not be null or empty", "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); } }}以这种方式使用它：
string[] x = new[] { "101133110", "101233210", "102533010", "101331310" };string longestCommon = x.GetLongestCommonSubstring(); // "10"
