a1 = [3,6,4] a2 = [1,2,3,4,5,7,8,9] ...? a1 is a subset of a2
set.subset?
require 'set' a1 = Set[3,4] a2 = Set[1,9] puts a1.subset?(a2)
输出:@H_502_11@
true
看到它在线工作:ideone@H_502_11@