Ruby methods for interview process.

ruby_methods

# method 1

# returns members of the Fibonacci series up to a certain value
def method_one(max)
  i1, i2 = 1, 1
  while i1 <= max
    yield i1
    i1, i2 = i2, i1+i2
  end
end

method_one(100) {|f| print f, " " }

# expected output
# 1 1 2 3 5 8 13 21 34 55 89 144 233 377 610 987


# method 2
# helper method on the Integer class that generates a stream of integers

def Integer.all
  Enumerator.new do |yielder, n: 0|
    loop { yielder.yield(n += 1) }
  end.lazy
end

p Integer.all.first(10)

# expected output
# [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

# Now how would you get the first 10 multiples of three?
p Integer.all.select {|i| (i % 3).zero? }.first(10)

# expected output
# [3, 6, 9, 12, 15, 18, 21, 24, 27, 30]

# multiples of three whose string representations are palindromes
def method_three?(n)
  n = n.to_s
  n == n.reverse
end

p Integer.all.select{|i| (i % 3).zero?}.select{|i| palindrome?(i)}.first(10)

# expected output
# [3, 6, 9, 33, 66, 99, 111, 141, 171, 222]