Crystal "almost" solution to Project Euler 111

111.cr

macro break_if_enough divisible, divisor, to_return = nil
  q, r = {{divisible}}.divmod {{divisor}}
  {% if to_return %}
    return false if r == 0
    return true if q <= {{divisor}}
  {% else %}
    break false if r == 0
    break true if q <= {{divisor}}
  {% end %}
end

prime? = -> {
  primes = [2, 3, 5] of Int32

  candidate = 5
  step = 4

  -> (n : Int64) {
    primes.each do |prime|
      break_if_enough n, prime, :return
    end

    loop do
      loop do
        candidate += step = 6 - step
        break if primes.each do |prime|
          break_if_enough candidate, prime
        end
      end
      primes << candidate
      break_if_enough n, candidate
    end
  }

}.call

raise  "3" unless prime?.call  3_i64
raise  "4"     if prime?.call  4_i64
raise  "5" unless prime?.call  5_i64
raise  "6"     if prime?.call  6_i64
raise  "7" unless prime?.call  7_i64
raise  "8"     if prime?.call  8_i64
raise  "9"     if prime?.call  9_i64
raise "10"     if prime?.call 10_i64
raise "11" unless prime?.call 11_i64

n = 6

r = (0..9).map do |i|
  s = 0
  g = 2
  x = (10**(n-1) - 1).to_i64
  while x < 10**n
    z = x += 2
    m = 0
    until z == 0
      z, b = z.divmod 10
      m += 1 if b == i
    end
    next if g > m
    next unless prime?.call x
    next s += x unless m > g
    s = x
    g = m
  end
  s
end

p r.sum