19/02/22 07:58:55.12 6TNKk8ap.net
>>279 Ruby
f = -> a {a[0..-2].join(', ').sub(/.\K\z/, ' and ') << a[-1].to_s}
(-1..3).each{|r| puts f[[*0..r]]} # =>
0
0 and 1
0, 1 and 2
0, 1, 2 and 3
19/02/22 07:58:55.12 6TNKk8ap.net
>>279 Ruby
f = -> a {a[0..-2].join(', ').sub(/.\K\z/, ' and ') << a[-1].to_s}
(-1..3).each{|r| puts f[[*0..r]]} # =>
0
0 and 1
0, 1 and 2
0, 1, 2 and 3