excel-sheet-column-title

convert_to_title.rb

# @param {Integer} n
# @return {String}
def convert_to_title(n)
    res = ''
  
    begin
      rem = n % 26
      n /= 26
      
      rem = if rem.zero?
          n -= 1
          25
      else
          rem - 1
      end

      res << [*('A'..'Z')].to_a[rem]      
    end while n.nonzero?
  
    res.reverse
end