ruby - Generate pseudo random string A-Z, 0-9

How can I generate an n-character pseudo random string containing only A-Z, 0-9 like SecureRandom.base64 without "+", "/", and "="? For example:

(0..n).map {(('1'..'9').to_a + ('A'..'Z').to_a)[rand(36)]}.join

Answer

Array.new(n){[*"A".."Z", *"0".."9"].sample}.join