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comp.lang.ruby

Re: [QUIZ] IP to Country (#139

James Koppel

9/19/2007 7:23:00 PM

I am extremely pleased with my solution this week:>ruby IPToCountry.rb 121.121.121.121MY 0.000000 0.000000 0.000000 ( 0.000000)Wrapping the code in 100.times {...}>ruby IPToCountry.rb 121.121.121.121MYMY...MYMY 0.062000 0.000000 0.062000 ( 0.078000)Hmmmm...clearly I'm using a supercomputer. :PMy solution uses no initialization run. Instead, it uses a binary search, making good use of IO#seek and IO#pos. It's a little atypical though - it uses different numbers to compare less than and greater than, and looking at a position really means looking at the first two numbers on the next line.Here's the code:require 'benchmark'puts Benchmark.measure { 100.times {dot_dec_ip = ARGV[0].chompdec_ip = dot_dec_ip[0..2].to_i << 24dot_dec_ip = dot_dec_ip[(dot_dec_ip.index(?.)+1)..-1]dec_ip += dot_dec_ip[0..2].to_i << 16dec_ip += dot_dec_ip[dot_dec_ip.index(?.)+1,3].to_i << 8#Last 8 bits are all in the same country; they don't matterdec_ip = dec_ipdataf = File.new("IPToCountry.csv")###Begin binary search, finding high and low#Hardcoded character offset of where to start. This should be the index of#a character on the last line of comments##Earlier versions used 0 or calculated this each iteration.#The former yielded bad results (for obvious reasons);#the latter doubled the time needed.low = 6603dataf.seek(0,IO::SEEK_END)flen = dataf.poshigh = flenwhile true if low == high - 1 puts "IP not assigned" break end mid = (low + high) >> 1 dataf.seek(mid,IO::SEEK_SET) dataf.gets dataf.getc range_start = dataf.gets('"') range_start.slice!(-1) range_start = range_start.to_i cmpno = dec_ip <=> range_start if cmpno == -1 high = mid next else dataf.read(2) range_end = dataf.gets('"') range_end.slice!(-1) range_end = range_end.to_i if (dec_ip <=> range_end) == 1 low = mid next else puts dataf.gets.match(/"(\w\w)"/)[1] break end endend}}----- Original Message ----From: Ruby Quiz <james@grayproductions.net>To: ruby-talk ML <ruby-talk@ruby-lang.org>Sent: Friday, September 14, 2007 7:31:41 AMSubject: [QUIZ] IP to Country (#139)The three rules of Ruby Quiz:1. Please do not post any solutions or spoiler discussion for this quiz until48 hours have passed from the time on this message.2. Support Ruby Quiz by submitting ideas as often as you can:http://www.ruby.... Enjoy!Suggestion: A [QUIZ] in the subject of emails about the problem helps everyoneon Ruby Talk follow the discussion. Please reply to the original quiz message,if you can.-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=This week's Ruby Quiz is to write a simple utility. Your program should acceptan IP address as a command-line argument and print out the two letter code forthe country that IP is assigned in. You can find a database for the matchingat: http://software77.net/cgi-bin/ip-country/g... keep the problem interesting though, let's write our programs with a focus onspeed and memory efficiency. $ time ruby ip_to_country.rb 68.97.89.187 US real 0m0.314s user 0m0.259s sys 0m0.053s ____________________________________________________________________________________Be a better Globetrotter. Get better travel answers from someone who knows. Yahoo! Answers - Check it out.http://answers.yahoo.com/dir/?link=list&sid...