ruby位数自动补齐

case:1

max = 0
b=["1","3","100","1000"]
b.each{|key|
  len = key.to_s.length
  (len>max)?(max=len):()
}

b.each{|key|
  puts "0"*(max - key.to_s.length)+key.to_s
}

case:2

15.times do |i|
  puts sprintf("%02d\n",i)
end