using System;

using System.Collections.Generic;

using System.Linq;

using System.Xml.Linq;

using System.Globalization;

​

public class Program

{

    public static void Main()

    {

        var result = "2020-01-16T14:29:17.9743131Z0";

        Console.WriteLine("dateTime : {0}", result);

        Console.WriteLine("result : {0}", formats.First(x => TryParseISO8601String(x, out DateTime d)));

    }

        static readonly string[] formats = { 

    // Basic formats

    "yyyyMMddTHHmmsszzz",

    "yyyyMMddTHHmmsszz",

    "yyyyMMddTHHmmssZ",

    // Extended formats

    "yyyy-MM-ddTHH:mm:sszzz",

    "yyyy-MM-ddTHH:mm:sszz",

    "yyyy-MM-ddTHH:mm:ssZ",

    // All of the above with reduced accuracy

    "yyyyMMddTHHmmzzz",

    "yyyyMMddTHHmmzz",

    "yyyyMMddTHHmmZ",

    "yyyy-MM-ddTHH:mmzzz",

    "yyyy-MM-ddTHH:mmzz",

    "yyyy-MM-ddTHH:mmZ",

    // Accuracy reduced to hours

    "yyyyMMddTHHzzz",

    "yyyyMMddTHHzz",

    "yyyyMMddTHHZ",

    "yyyy-MM-ddTHHzzz",

    "yyyy-MM-ddTHHzz",

    "yyyy-MM-ddTHHZ"

    };

​

    public static bool TryParseISO8601String(string str, out DateTime d)

    {

        return DateTime.TryParseExact(str, formats, CultureInfo.InvariantCulture, DateTimeStyles.None, out d);

    }

}