Order of 1: O(1)

big-o-benchmarks-o(1).rb

require 'benchmark'

def benchmark
  time_in_seconds = Benchmark.realtime { yield }
  time_in_milliseconds(time_in_seconds)
end

def time_in_milliseconds(time_in_seconds)
  (time_in_seconds * 1000).to_s + ' ms'
end

one_million_elements = (1..1_000_000).to_a
ten_million_elements = (1..10_000_000).to_a
one_hundred_million_elements = (1..100_000_000).to_a

puts benchmark { one_million_elements[853_123] }
puts benchmark { ten_million_elements[8_853_123] }
puts benchmark { one_hundred_million_elements[92_853_923] }

# Here's an example of the output
# > ruby test.rb
# 0.0030390219762921333 ms
# 0.000693020410835743 ms
# 0.0005030306056141853 ms