My solution in C# builds the staircase row by row. For each row i (from 1 to n):

I print (n - i) spaces to align it to the right

Then I print i hash symbols (#)

This way the output grows step by step until the full staircase is printed.

    public static void staircase(int n)
{
    for(int i =1; i <= n; i++){
        int spaces = n - i;
        int hashtags = i;
        string staircase = new string(' ', spaces) + new string('#', hashtags);
        Console.WriteLine(staircase);
    }
}