Solve 2018/05

2018/05/solve.py

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+import sys
+
+# PART 1
+
+def load_polymer(filename):
+	pols = []
+	with open(filename, "r") as f:
+		for line in f:
+			pols.append(list(line[:-1]))
+	return pols
+
+def naive_react(pol):
+	for i in range(len(pol) - 1):
+		if pol[i].lower() == pol[i+1].lower() and pol[i] != pol[i+1]:
+			print("Naive react says: More reacting is possible.")
+
+def react(pol):
+	start = 0
+	while True:
+		i = start
+		while i < len(pol) - 1:
+			if pol[i].lower() == pol[i+1].lower() and pol[i] != pol[i+1]:
+				del pol[i]
+				del pol[i]
+				start = max(0, start - 1)
+				break
+			elif i == start + 1:
+				start = i
+			i += 1
+		else:
+			return
+
+def result(pol):
+	l = pol.copy()
+	#print("".join(l))
+	react(l)
+	#print("->", "".join(l))
+	naive_react(l)
+	return len(l)
+
+# PART 2
+
+def removable_chars(pol):
+	return set(c.lower() for c in pol)
+
+def remove(pol, char):
+	return [c for c in pol if c.lower() != char.lower()]
+
+def find_obstructing(pol):
+	results = []
+	chars = removable_chars(pol)
+	for c in sorted(chars):
+		l = remove(pol, c)
+		n = result(l)
+		print("Removed", c, "-> length", n)
+		results.append(n)
+	return min(results)
+
+def main(filename):
+	print(f"Solutions for {filename}")
+	pols = load_polymer(filename)
+	for pol in pols:
+		length = result(pol)
+		print(f"Part 1: {length}")
+		best_result = find_obstructing(pol)
+		print(f"Part 2: {best_result}")
+
+if __name__ == "__main__":
+	for filename in sys.argv[1:]:
+		main(filename)

2018/05/test_input.txt

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+dabAcCaCBAcCcaDA

2018/05/test_inputs.txt

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+aA
+abBA
+abAB
+aabAAB
+dabAcCaCBAcCcaDA