day-5.py

def puzzleSolutionPartOne(puzzle): 
	lhs = ""
	units = []
	react = lambda a,b: a.lower() == b.lower() and a != b

	for candidate in puzzle:
		if lhs == "": 
			lhs = candidate
			continue

		if not react(lhs, candidate):
			units.append(lhs)
			lhs = candidate
		else:
			if units:
				lhs = units.pop()
			else:
				lhs = ""

	units.append(lhs)	
	return len(units)

def puzzleSolutionPartTwo(puzzle):
	removeUnits = lambda puzzle, chr: filter(lambda x: x != chr.lower() and x != chr.upper(), puzzle )
	removedUnits = {}
	for candidate in puzzle:
		candidate = candidate.lower()
		if not candidate in removedUnits:
			removedUnits[candidate] = puzzleSolutionPartOne(removeUnits(puzzle, candidate))

	return min( removedUnits.values() )	


puzz = "dabAcCaCBAcCcaDA"
puzzle = open("puzzle.txt", "r").read()

print "Solution 1: " + str( puzzleSolutionPartOne(puzzle) )
print "Solution 2: " + str( puzzleSolutionPartTwo(puzzle) )