aocday1

part1.rb

ints = File.readlines("input.txt").map(&:to_i)
puts ints.sum

part2.rb

require "set"
ints = File.readlines("input.txt").map(&:to_i)
sum = 0
observations = [sum].to_set
while true
  ints.each do |i|
    sum += i
    if observations.include?(sum)
      puts "sum=#{sum}"
      exit
    end
    observations << sum
  end
end