I'm working through a course now, and was tasked with the following:Write a function, no_repeats(year_start, year_end), which takes a range of years and outputs those years which do not have any repeated digits.You should probably write a helper function, no_repeat?(year) which returns true/false if a single year doesn't have a repeat.I did not know about each_char yet, so I wrote the following:def no_repeats(year_start, year_end)  (year_start..year_end).to_a.keep_if {|year| no_repeat?(year)}enddef no_repeat?(year)  year_array = year.to_s.split(//)  year_array == year_array.uniqendI'm wondering if:there is an easier way to make an array from a string with no spacesthere is a way to convert each character in a number to an item in a single array without converting the number to a string firstthere is a better way to do this problemThis is the model solution for a beginner:def no_repeats(year_start, year_end)  no_repeats = []  (year_start..year_end).each do |yr|    no_repeats << yr if no_repeat?(yr)  end  no_repeatsenddef no_repeat?(year)  chars_seen = []  year.to_s.each_char do |char|    return false if chars_seen.include?(char)    chars_seen << char  end  return trueendI'm also wondering about the advantages and disadvantages of my code compared to the model solution. I kind of get that shorter code is better, and readability matters. I don't know how to test code for time yet.
Outputting years with no repeated digits
beginner;strings;ruby;datetime
The model solution they propose is very unidiomatic, your code is far better. I'd just made some minor changes:Use String#chars instead of String#split(//).Use Enumerable#select? instead of Array#keep_if to avoid modifying data in-place. It's better to work with immutable streams of data (with methods from Enumerable).I'd write:def no_repeats(year_start, year_end)  (year_start..year_end).select { |year| no_repeat?(year) }enddef no_repeat?(year)  year_digits = year.to_s.chars  year_digits == year_digits.uniqend