Ruby - Does array A contain all elements of array B

You can try this

a.sort.uniq == b.sort.uniq

(a-b).empty?

And if [1,2,2] != [1,2] in your case you can:

a.group_by{|i| i} == b.group_by{|i| i}

This should work for what you need:

(a & b) == b

You could use Ruby's Set class:

>> require 'set' #=> true
>> a = [*1..5] #=> [1, 2, 3, 4, 5]
>> b = [*1..3] #=> [1, 2, 3]
>> a.to_set.superset? b.to_set #=> true

For small arrays I usually do the same as what fl00r suggested:

>> (b-a).empty? #=> true

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