Day 1, 2017 - ruby

Author: scottshepard

2017/day01.rb

@@ -0,0 +1,19 @@
+if ARGV.length > 0
+  input = ARGV[0]
+else
+  input = File.read('inputs/day01.txt')
+end
+
+def checksum(num)
+  sum = 0
+  digits = num.split('')
+  fulldigits = digits + digits
+  for i in 0...digits.length
+    if(digits[i] == fulldigits[i+1])
+      sum += digits[i].to_i
+    end
+  end
+  sum
+end
+
+puts checksum(input)

Gemfile

@@ -0,0 +1,3 @@
+source "https://rubygems.org"
+
+ruby "2.4.2"