100 (and more) doors in ruby using threading.

lockers.rb

Size = ARGV.first.to_i
doors = Array.new(Size, false)

(1..Size).each do |pass|
    (0...Size).each do |pos|
        doors[pos] = !doors[pos] if (pos+1) % pass == 0
    end 
end

doors.each_with_index {|val, pos| puts pos+1 if val}

lockers3.rb

Size = ARGV.first.to_i
Cpus = 4 
raise "Devision error" if Size % Cpus != 0
Cpu_share = Size / Cpus

doors = Array.new(Size, false)
threads = []

Cpus.times do |cpu|
    threads << Thread.new(Cpu_share*cpu) do |start|
        (1..Cpu_share).each do |pass|
            pass += start
            (0...Size).each do |pos|
                doors[pos] = !doors[pos] if (pos + 1) % pass == 0
            end 
        end 
    end 
end

threads.each {|thr| thr.join}

doors.each_with_index {|val, pos| puts pos+1 if val}

test3.sh

#!/bin/bash

NUM=$1

NONE='\033[00m'
BOLD='\033[01m'
RED='\033[01;31m'
GREEN='\033[01;32m'

TIME="/usr/bin/time -f 'Run time: %E, CPU usage: %P, Max memory: %MKb'"

toilet -f future $NUM
echo -e "${GREEN}Single thread$NONE"
echo -e "${BOLD}Ruby$NONE"
eval $TIME ruby lockers.rb $NUM
echo -e "${BOLD}jRuby$NONE"
eval $TIME jruby lockers.rb $NUM

echo -e "${GREEN}Multi thread (Limit thread number)$NONE"
echo -e "${BOLD}Ruby$NONE"
eval $TIME ruby lockers3.rb $NUM
echo -e "${BOLD}jRuby$NONE"
eval $TIME jruby lockers3.rb $NUM

echo -e "${RED}Finished$NONE"