2020 day 13 solution

Dependencies

• [2] B527MN66 Solve day 1 for 2020

Change contents

• file addition: day13.rb (----------)
  [2.17]
  + raise "Expected Filename" unless ARGV[0]

  + file = File.open(ARGV[0])

  + input = file

  + .readlines

  + .map{|line| line.split(',').map{|s| s == 'x' ? 'x' : s.to_i } }

  + file.close

  +

  + start_time = input[0][0]

  +

  + unless ARGV[1] && ARGV[1] == "2"

  + result = input[1]

  + .select{|route| route != 'x' }

  + .map do |route|

  + m = start_time % route

  + {

  + id: route,

  + wait: m == 0 ? 0 : route - m,

  + }

  + end.min{|a, b| a[:wait] <=> b[:wait] }

  +

  + puts result[:id] * result[:wait]

  + else

  + result = 0

  + factor = 1

  + input[1].each_with_index.select{|route,_| route != 'x' }.each do |(route,ix)|

  + while (result + ix) % route != 0

  + result += factor

  + end

  + factor = factor.lcm(route)

  + end

  + puts result

  + end