I’ve been ill today, but there’s no better medicine than an easy Project Euler problem! I tried doing some bitwise magic, but in the end my simplest solution proved the fastest as well.
Find the sum of all numbers, less than one million, which are palindromic in base 10 and base 2.
def palindrome? s s == s.reverse end sum = (1..1_000_000).inject(0) do |sum, n| sum += palindrome?(n.to_s) && palindrome?(n.to_s 2) ? n : 0 end puts sum