gistfile1.txt

# Bob is preparing to pass IQ test. The most frequent task in this test is 
# to find out which one of the given numbers differs from the others. Bob 
# observed that one number usually differs from the others in evenness. 
# Help Bob — to check his answers, he needs a program that among the given 
# numbers finds one that is different in evenness, and return a position of this number.

# ! Keep in mind that your task is to help Bob solve a real IQ test, which 
# means indexes of the elements start from 1 (not 0)
# Examples :
# iq_test("2 4 7 8 10") => 3 // Third number is odd, while the rest of the numbers are even
# iq_test("1 2 1 1") => 2 // Second number is even, while the rest of the numbers are odd

def iq_test(number_sequence)
  number_sequence.split(' ').map(&:to_i).each_with_index.inject({even: [], odd: []}) do |inject_hash, element_pair|
    element, index = element_pair
    inject_hash[:even].push(index + 1) if element.even?
    inject_hash[:odd].push(index + 1) if element.odd?

    return inject_hash[:even].pop if inject_hash[:odd].size >= 2 && inject_hash[:even].size == 1
    return inject_hash[:odd].pop if inject_hash[:even].size >= 2 && inject_hash[:odd].size == 1

    inject_hash
  end
end

puts iq_test("2 4 7 8 10")
puts iq_test("1 2 1 1")