[C#] Chuyển số thập nhân sang cơ số 32 - http://goclaptrinh.io/cms/beginner/csharp-crockford-base32-numbers/

Program.cs

using System;

class GocLapTrinh
{
	static int NhapSoThapPhan()
	{
		Console.Write("Nhap so thap phan: ");
		return int.Parse(Console.ReadLine() ?? string.Empty);
	}

	static string NhapSoBase32()
	{
		Console.Write("Nhap so o he co so 32 (bang ma Crockford Base32): ");
		return Console.ReadLine() ?? string.Empty;
	}

	static string DoiSangBase32(int n)
	{
		var base32 = "0123456789ABCDEFGHJKMNPQRSTVWXYZ";
		var s = "";
		while (n > 0)
		{
			s = base32[n % 32] + s;
			n /= 32;
		}
		return s;
	}

	static int DoiSangThapPhan(string s)
	{
		var base32 = "0123456789ABCDEFGHJKMNPQRSTVWXYZ";
		var n = 0;
		s = s.ToUpper().Replace('I', '1').Replace('L', '1').Replace('O', '0').Replace('U', 'V');
		foreach (var c in s)
		{
			var i = base32.IndexOf(c);
			if (i == -1) return -1; // co ky tu khong hop le!
			n = n * 32 + i;
		}
		return n;
	}

	static void Main()
	{
		var n = NhapSoThapPhan();
		Console.WriteLine($"So thap phan: {n}, doi sang base32: {DoiSangBase32(n)}");

		var s = NhapSoBase32();
		Console.WriteLine($"So base32: {s}, doi sang thap phan: {DoiSangThapPhan(s)}");
	}
}