Add Day19 solution. Used regexes and slicing, even though there were …

…probably better solutions.

Day19/Day19.py

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+from collections import defaultdict
+import re
+
+replacements = defaultdict(list)
+molecule = ''
+finalMolecules = []
+
+with open('Day19Input.txt', 'r') as file:
+	for line in file:
+		line = line.strip()
+
+		if '=>' not in line:
+			print('Final Molecule: \'%s\'' % line)
+			molecule = line
+		else:
+			molecules = line.split(' => ')
+			replacements[molecules[0]].append(molecules[1])
+			print('Replace %s with %s' % (molecules[0], molecules[1]))
+
+for key in replacements:
+	print("Finding: %s" % key)
+	for replacement in replacements[key]:
+		for match in re.finditer(key, molecule):
+			#print(molecule.replace(match, replacements[key]))
+			print(match)
+			newMolecule = molecule[0:match.start()]
+			newMolecule += replacement
+			newMolecule += molecule[match.end():]
+			print("New molecule: %s" % newMolecule)
+			# Look https://docs.python.org/3/library/re.html#match-objects for stuff on the match object returned
+			finalMolecules.append(newMolecule)
+
+print(len(set(finalMolecules)))

Day19/Day19Input.txt

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+Al => ThF
+Al => ThRnFAr
+B => BCa
+B => TiB
+B => TiRnFAr
+Ca => CaCa
+Ca => PB
+Ca => PRnFAr
+Ca => SiRnFYFAr
+Ca => SiRnMgAr
+Ca => SiTh
+F => CaF
+F => PMg
+F => SiAl
+H => CRnAlAr
+H => CRnFYFYFAr
+H => CRnFYMgAr
+H => CRnMgYFAr
+H => HCa
+H => NRnFYFAr
+H => NRnMgAr
+H => NTh
+H => OB
+H => ORnFAr
+Mg => BF
+Mg => TiMg
+N => CRnFAr
+N => HSi
+O => CRnFYFAr
+O => CRnMgAr
+O => HP
+O => NRnFAr
+O => OTi
+P => CaP
+P => PTi
+P => SiRnFAr
+Si => CaSi
+Th => ThCa
+Ti => BP
+Ti => TiTi
+e => HF
+e => NAl
+e => OMg
+ORnPBPMgArCaCaCaSiThCaCaSiThCaCaPBSiRnFArRnFArCaCaSiThCaCaSiThCaCaCaCaCaCaSiRnFYFArSiRnMgArCaSiRnPTiTiBFYPBFArSiRnCaSiRnTiRnFArSiAlArPTiBPTiRnCaSiAlArCaPTiTiBPMgYFArPTiRnFArSiRnCaCaFArRnCaFArCaSiRnSiRnMgArFYCaSiRnMgArCaCaSiThPRnFArPBCaSiRnMgArCaCaSiThCaSiRnTiMgArFArSiThSiThCaCaSiRnMgArCaCaSiRnFArTiBPTiRnCaSiAlArCaPTiRnFArPBPBCaCaSiThCaPBSiThPRnFArSiThCaSiThCaSiThCaPTiBSiRnFYFArCaCaPRnFArPBCaCaPBSiRnTiRnFArCaPRnFArSiRnCaCaCaSiThCaRnCaFArYCaSiRnFArBCaCaCaSiThFArPBFArCaSiRnFArRnCaCaCaFArSiRnFArTiRnPMgArF