18/04/21 22:36:51.73 QInDazsH.net
>>928 ruby
puts a[0...-1].inject(''){|r,s| r << s << ',' } + a.last
puts a.inject(''){|r,s| r << s << ',' }.chop
puts a.map{|s| [s, ','] }.join.chop
b = a.join
a[0...-1].inject(0){|r,s| r += s.length + 1; b = b.insert(r-1, ','); r }
puts b