2019 day 4 part 1

Dependencies

• [2] TCCBGQEU 2019 day 1

Change contents

• file addition: day4.rb (----------)
  [2.7]
  + def pairwise e

  + Enumerator.new do |y|

  + a = e.next

  + while true

  + b = e.next

  + y.yield a,b

  + a = b

  + end

  + rescue StopIteration

  + end

  + end

  +

  + def next_d(d,c)

  + d == true || d == c || c

  + end

  +

  + def build_candidates(d,s)

  + Enumerator.new do |y|

  + if s.length == 0

  + y.yield [] if d == true

  + else

  + r = s[0]

  + Enumerator.new do |y2|

  + (r.begin .. r.end).each do |c|

  + y2.yield(c, s[1 ... s.length].map do |m|

  + (c != r.begin ? c : [c, m.begin].max) ..

  + (c == r.end ? m.end : '9')

  + end)

  + end

  + end.each do |c,sn|

  + build_candidates(next_d(d,c), sn).each do |t|

  + y.yield([c] + t)

  + end

  + end

  + end

  + end

  + end

  +

  + def solve(a,b)

  + build_candidates(false,a.to_s.chars.zip(b.to_s.chars).map do |l,h|

  + l .. h

  + end).lazy.map{|r| r.join("").to_i }

  + end

  +

  + # puts solve(ARGV[0], ARGV[1]).count