stitch-a-ton/WebApp/Helper.cs

namespace WebApp;

public static class Helper
{
    public static string ToLetters(int number)
    {
        var result = "";
        while (number > 0)
        {
            number--; // Adjust for 1-based indexing
            char letter = (char)('A' + (number % 26));
            result = letter + result;
            number /= 26;
        }
        return result;
    }

    public static (int Row, int Col) ToRowCol(string letters)
    {
        int row = 0;
        int col = 0;
        foreach (var item in letters)
        {
            if (item >= 'A')
            {
                row = row * 26 + (item - 'A' + 1);
            }
            else if (item >= '0')
            {
                col = col * 10 + (item - '0');
            }
        }

        return (row, col);
    }
}