use redis to store autocomplete feature

gistfile1.rb

require "redis"

redis = Redis.new

def get_prefixes word
  Array.new(word.length) do |i|
    if i == word.length - 1
      "#{ word }*"
    else
      word[0..i]
    end
  end
end

redis.del "autocomplete"

argv = []
File.open("content.txt").each_line do |word|

  get_prefixes(word.chomp).each do |prefix|
    argv << [0, prefix]
  end

end

redis.zadd "autocomplete", argv

while prefix = gets.chomp do
  result = []
  if rank = redis.zrank("autocomplete", prefix)
    redis.zrange("autocomplete", rank + 1, rank + 100).each do |words|
      if words[-1] == "*" && prefix == words[0..prefix.length - 1]
        result << words[0..-2]
      end
    end
  end
  puts result
end