C# accepted solution - list sort only letter-logs
as the List.Sort(..) isn\'t a stable sort -  sort only letterlogs and add digit-logs at the end\n\n\npublic string[] ReorderLogFiles(string[] logs)\n{\n\tList<s
as the List.Sort(..) isn\'t a stable sort -  sort only letterlogs and add digit-logs at the end\n\n```\npublic string[] ReorderLogFiles(string[] logs)\n{\n\tList<string> letterLogs = new List<string>(); \n\tList<string> digitLogs = new List<string>();\n\tforeach (var log in logs)\n\t{\n\t\tif (char.IsDigit(log[log.IndexOf(\' \') + 1]))\n\t\t{\n\t\t\tdigitLogs.Add(log);\n\t\t}\n\t\telse\n\t\t{\n\t\t\tletterLogs.Add(log);\n\t\t}\n\t}\n\n\tletterLogs.Sort((a, b) =>\n\t{\n\t\tstring a_substr = a.Substring(a.IndexOf(\' \') + 1);\n\t\tstring b_substr = b.Substring(b.IndexOf(\' \') + 1);\n\t\tvar result = a_substr.CompareTo(b_substr);\n\t\tif (result == 0)\n\t\t{\n\t\t\tresult =  a.Substring(0, a.IndexOf(\' \')).CompareTo(b.Substring(0, b.IndexOf(\' \')));\n\t\t}\n\t\treturn result;\n\t});\n      \n\tletterLogs.AddRange(digitLogs);\n\treturn letterLogs.ToArray();\n}\n```
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