OneHourQuestions.rb

#1
class Question1
  class << self
    def case_for()
      total = 0
      for i in 1..10 do
        total += i
      end
      
      puts total
    end
    
    def case_while()
      i = 0
      total = 0
      while i <= 10 do
       total += i
       i += 1
      end
      puts total
    end
    
    def case_recursion(total = 0 , i = 1)
      if i > 10
        puts total
        return
      end
      
      total += i
      i += 1
      
      case_recursion(total, i)
    end
  end
  
  case_for
  case_while
  case_recursion
end

#2
class Question2
  class << self
    def join_two_array() 
      p %w(1 2 3).zip(%w(a b c)).flatten
    end
  end
  join_two_array
end

#3
class Quetion3
  class << self
    def calc_fibonacci_total
      p fibonacci(10).inject(&:+)
    end
    
    def fibonacci(n)
      [].tap do |arr|
        raise StandardError if n < 2
        arr.push 0, 1
        
        (2..n - 1).each do |i|
          arr << arr[i - 2] + arr[i - 1]
        end
      end
    end
  end
  
  calc_fibonacci_total
end

#4
class Question4
  class << self
    def max_pattern
      puts [50, 2, 1, 9].permutation(4).map(&:join).max
    end
  end
  
  max_pattern
end