solved part 2

day01/solution.rb

@@ -2,4 +2,14 @@
 # Sum all numbers in the text file.
 
 # Part 1
-sum = File.readlines('./input').map { |line| line.to_i)}.sum
+sum = File.readlines('./input').map { |line| line.to_i}.sum
+
+# Part 2
+numbers = File.readlines('./input').map { |line| line.to_i}
+freqs = [0]
+
+numbers.cycle do |num|
+    freqs.push(freqs[-1] + num)
+    break if freqs[0..-2].include?(freqs[-1])
+end
+puts freqs[-1]