某クロッシング問題をredisで解いてみた: ( https://codeiq.jp/ace/yuki_hiroshi/q432 )

redis-crossing.rb

#!/usr/env/ruby -v

require 'benchmark'
measure = Benchmark.measure {
  require 'redis'
  redis = Redis.new
  redis.del :ray

  INPUT = 'crossing.txt'

  rays = []
  open(INPUT).read.each_line { |line|
    rays << line.chomp.to_i - 1
  }
  p rays.count
  puts

  crossing_count = 0
  rays.each.with_index do |ray, i|

    redis.zadd :ray, ray, ray
    crossing_count += redis.zcount(:ray, ray + 1, '+inf')

    puts "#{i}, #{Time.now}" if i % 10000 == 0
  end

  puts
  p crossing_count

}
puts Benchmark::CAPTION
puts measure #=> 45秒ぐらい