return-the-unique.rb

# return the unique elements of this array:
# a = []
# 10000000.times{a.push(rand(100))}
# no array.uniq please

# extra credit -- in one function, count all the occurrences of each element of a

a = []
10000000.times{a.push(rand(100))}

b = []
count_hash = Hash.new(0)

while a.count > 0 do
  pick = a.sample
  count_hash[pick] = a.count(pick)
  b.push a.delete pick
end

b.inspect
count_hash.inspect

excellent! I was going for the use of Set -- but this is excellent.
s = Set.new
a.map{|e| Set.add(e)}

Set is the great unused class