Ruby Quiz 39

Here is my solution to Ruby Quiz 39: Sampling. This solution, which takes roughly 1.75 minutes to run realtime (0.010 sec user time) is so short, I present it here in its entirety:

#! /usr/bin/env ruby

require 'set'

def sample(members, range)
  selected =
  members.times {
    val = rand(range)
    val = rand(range) until selected.add?(val)

puts sample(ARGV[0].to_i, ARGV[1].to_i).join("\n")

This solution is completely out-of-the-box. I played with a few optimizations, without looking for this algorithm anywhere online. Instead of using a Set (which is backed by a Hash), I wanted to create a range-length array and mark each selected value using that array. With a range of 10e9, my machine ran out of memory.

Disk I/O took about 45 seconds of the total time. There’s probably a way to speed that up.

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