anagram.rb

def isAnagramOfPalindrome (s)
  return 0 if s.length < 2 # no need to check 1 or 0 character words
  
  # # returns letters in hash 
  # f.e. "aabcba" ===> {"c"=>["c"], "b"=>["b", "b"], "a"=>["a", "a", "a"]}
  letters = s.split("").group_by{|x| x} 

  # selects these arrays where size is odd and checks if it's empty
  return 1 if letters.select{|key,value| value.length % 2 != 0 }.empty?
  return 0 # return for clarity
end

puts isAnagramOfPalindrome("addddaaa") # >> 1
puts isAnagramOfPalindrome("x") # >> 0

binary_gap.rb

def binary_gap(n)
  n.to_s(2).scan(/[0]+/).group_by(&:size).max.first rescue 0
end

puts 15.to_s(2) # >> 1111
puts binary_gap(15) # >> 0
puts 1041.to_s(2) # >> 10000010001
puts binary_gap(1041) # >> 5

symmetry.rb

def symmetryPoint (s)
  len = s.length
  return 0 if len <= 1
  return -1 if len % 2 == 0
  if s[0..len/2-1] == s[len/2+1..len].reverse
    len/2
  else
    -1
  end
end

puts symmetryPoint("xoxox") # >> 2
puts symmetryPoint("xoxoxg") # >> -1