euler67.rb

   1 require 'logger'
   2
   3 $triangle = File.readlines('euler67-triangle.txt').map {|line| line.chomp.split.map {|s| s.to_i}}
   4
   5 def find_best(triangle)
   6   log = Logger.new(STDERR)
   7   log.level = Logger::WARN
   8   last_line_totals = [0]
   9   this_line_totals = []
  10   triangle.each do |line|
  11     log.info {"Checking line #{line}"}
  12     this_line_totals = []
  13     line.each_index do |i|
  14       this_line_totals << [i == 0 ? 0 : last_line_totals[i-1] + line[i],
  15                            i == last_line_totals.length ? 0 : last_line_totals[i] + line[i]].max
  16     end
  17     log.info {"Best totals for line #{line} are #{this_line_totals}"}
  18     last_line_totals = this_line_totals
  19   end
  20   log.close
  21   this_line_totals.max
  22 end
  23
  24 if __FILE__==$0
  25   puts find_best $triangle
  26 end