Day 9

09.py

@@ -0,0 +1,26 @@
+#!/usr/bin/python3
+
+import re
+
+# Version of parse() that recursively parses repeated sections
+rparse = lambda x: parse(x, rparse)
+
+def parse(data, rfun=len):
+	# Find the first bracketed part (if one exists)
+	index, bracket = data.find('('), data.find(')')
+	if index == -1: return len(data)
+
+	# Grab the (NxR) values from the brackets
+	num, reps = map(int, data[index+1:bracket].split('x'))
+	
+	# Return the initial, non-repeated data, plus...
+	return (len(data[:index])
+			# the repeated data, potentially parsed recursively, plus...
+	        + reps * rfun(data[bracket+1:bracket+1+num]) 
+	        # the remainder of the string, parsed
+	        + parse(data[bracket+1+num:], rfun))
+
+with open('09.txt', 'r') as file:
+    input = re.sub('\s+', '', file.read())
+    print(parse(input))
+    print(rparse(input))