def min_len(a)
  h = Hash.new { |h,k| h[k] = [] }
  array.each.with_object(h)
       .with_index { |(i, h), idx| h[i] << idx }
       .values.map { |a| [a.size, a.last - a.first] }
       .sort       { |i1, i2| [i1.first, i1.last] <=> [i2.first, i2.last] }
       .last.last
end

def min_len(a)
a.each.with_object({}).with_index{|(i,h),x|h[i]=(h[i]||[])<<x}.values.map{|a|[a.size,a[-1]-a[0]]}.sort{|a,b|[a[0],a[-1]]<=>[b[0],b[-1]]}[-1][-1]+1
end