desafio_da_senha.rb

a = [6, 2, 8, 4, 7]
# 2 numeros corretos, 1 na posição certa

b = [0, 5, 9, 4, 7]
# 2 números corretos, mas na posição errada

c = [1, 3, 0, 8, 7]
# 1 número correto na posição correta

d = [9, 7, 6, 3, 2]
# 3 númeors corretos, mas no lugar errado

e = [3, 0, 4, 7, 9]
# 1 número correto, mas no lugar errado

def positional_matches(iteration, num, match_count)
  matches = 0
  for i in 0..4 do
    matches += 1 if iteration[i] == num[i]
  end
  match_count == matches
end

possibilities = []
for i in 0..99999 do
  possible_solution = i.to_s.rjust(5, '0').split('').map(&:to_i)  

  a_ok = (possible_solution & a).count == 2 && positional_matches(possible_solution, a, 1)
  b_ok = (possible_solution & b).count == 2 && positional_matches(possible_solution, b, 0)
  c_ok = (possible_solution & c).count == 1 && positional_matches(possible_solution, c, 1)
  d_ok = (possible_solution & d).count == 3 && positional_matches(possible_solution, d, 0)
  e_ok = (possible_solution & e).count == 1 && positional_matches(possible_solution, e, 0)

  possibilities << possible_solution if a_ok && b_ok && c_ok && d_ok && e_ok
end

possibilities