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def assert_equal(x, y)
return if x == y
raise "Expected `#{x.inspect}`, got `#{y.inspect}`"
end
class Store
def initialize
@hash = Hash.new do |hash, key|
hash[key] = []
end
end
# time: O(1) + O(logn)
# space: O(1)
def get(key, at: nil)
bucket = @hash[key]
return if bucket[-1].empty?
if at
bucket[-1].bsearch { |x| x <= at }[-1]
else
bucket[-1][-1]
end
end
# time: O(1)
# space: O(1)
def set(key, value)
@hash[key] << [Time.now.to_i, value]
end
end
store = Store.new
store.set(:cart, 0)
now = Time.now.to_i
assert_equal(0, store.get(:cart))
store.set(:cart, 3)
assert_equal(3, store.get(:cart))
assert_equal(0, store.get(:cart, at: now))
puts "YAY!"
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