Add day 12

1 files changed, 39 insertions, 0 deletions

diff --git a/12/a.rb b/12/a.rb
new file mode 100644
index 0000000..e47babe
--- /dev/null
+++ b/12/a.rb
@@ -0,0 +1,39 @@
+instructions = File.readlines('input.txt').map do |line|
+  [line.slice(0, 1), line.slice(1, line.length).to_i]
+end
+
+n = 0
+e = 0
+direction = 0
+
+instructions.each do |instruction|
+  case instruction[0]
+  when 'N'
+    n += instruction[1]
+  when 'S'
+    n -= instruction[1]
+  when 'E'
+    e += instruction[1]
+  when 'W'
+    e -= instruction[1]
+  when 'F'
+    case direction
+    when 0
+      e += instruction[1]
+    when 90
+      n += instruction[1]
+    when 180
+      e -= instruction[1]
+    when 270
+      n -= instruction[1]
+    end
+  when 'L'
+    direction += instruction[1]
+    direction %= 360
+  when 'R'
+    direction -= instruction[1]
+    direction %= 360
+  end
+end
+
+puts n.abs + e.abs