cleanup and catchup

2021/03/03.py

@@ -2,27 +2,78 @@ report = []
 
 with open("input.txt") as f:
 	lines = f.read().split('\n')
-	for line in lines:
-		report.append(line)
+for line in lines:
+	report.append(line)
 
 gamma = ''
-power = 2 ** len(report[0]) - 1
-
 for i in range(len(report[0])):
-    ones_count = 0
-    for number in report:
-        if number[i] == '1':
-            ones_count += 1
+	ones_count = 0
+	for number in report:
+		if number[i] == '1':
+			ones_count += 1
 
-    half = len(report) / 2
-    if ones_count > half:
-        gamma += '1'
-    else:
-        gamma += '0'
+	half = len(report) / 2
+	if ones_count > half:
+		gamma += '1'
+	else:
+		gamma += '0'
 
+power = 2 ** len(gamma) - 1
 gamma = int(gamma, 2)
 epsilon = power - gamma
 part1 = gamma * epsilon
 print(part1)
 
-o2 = co2 = 0
+
+o2_candidates = set()
+co2_candidates = set()
+for number in report:
+	o2_candidates.add(number)
+	co2_candidates.add(number)
+
+for i in range(len(report[0])):
+	if len(o2_candidates) == 1:
+		break
+	# first pass: count the bits in each position
+	ones_count = 0
+	zeros_count = 0
+	for number in o2_candidates:
+		if number[i] == '0':
+			zeros_count += 1
+		else:
+			ones_count += 1
+	# Keep 1, unless 0 is more common.
+	if zeros_count > ones_count:
+		keep = '0'
+	else:
+		keep = '1'
+	# second pass: filter out the candidates
+	for number in o2_candidates.copy():
+		if number[i] != keep:
+			o2_candidates.remove(number)
+
+for i in range(len(report[0])):
+	if len(co2_candidates) == 1:
+		break
+	# first pass: count the bits in each position
+	ones_count = 0
+	zeros_count = 0
+	for number in co2_candidates:
+		if number[i] == '0':
+			zeros_count += 1
+		else:
+			ones_count += 1
+	# Keep 0, unless 1 is less common.
+	if ones_count < zeros_count:
+		keep = '1'
+	else:
+		keep = '0'
+	# second pass: filter out the candidates
+	for number in co2_candidates.copy():
+		if number[i] != keep:
+			co2_candidates.remove(number)
+
+o2 = int(o2_candidates.pop(), 2)
+co2 = int(co2_candidates.pop(), 2)
+part2 = o2 * co2
+print(part2)

2021/07/07.py

@@ -1,24 +1,24 @@
 with open("input.txt") as f:
-    crabs = [int(x) for x in f.read().split(',')]
+	crabs = [int(x) for x in f.read().split(',')]
 
 from statistics import median, mean
 from math import floor, ceil
 
 def part1(crabs):
-    m = int(median(crabs)) # the median is the midpoint
-    offsets = [abs(x-m) for x in crabs] # that will be used to calculate simple cost.
-    return sum(offsets)
+	m = int(median(crabs)) # the median is the midpoint
+	offsets = [abs(x-m) for x in crabs] # that will be used to calculate simple cost.
+	return sum(offsets)
 
 print(part1(crabs))
 
 def part2(crabs):
-    def cost(d):
-        return d*(d+1)//2 # sum of successive integers = triangle numbers.
-    # because the mean is not an integer,
-    m1 = floor(mean(crabs)) # we might need the floor,
-    m2 = ceil(mean(crabs)) # or we might need the ceiling.
-    fuel1 = [cost(abs(x-m1)) for x in crabs] # we calculate both costs
-    fuel2 = [cost(abs(x-m2)) for x in crabs] # because it could be either one.
-    return min([sum(fuel1), sum(fuel2)]) # just take the lesser of the two.
+	def cost(d):
+		return d*(d+1)//2 # sum of successive integers = triangle numbers.
+	# because the mean is not an integer,
+	m1 = floor(mean(crabs)) # we might need the floor,
+	m2 = ceil(mean(crabs)) # or we might need the ceiling.
+	fuel1 = [cost(abs(x-m1)) for x in crabs] # we calculate both costs
+	fuel2 = [cost(abs(x-m2)) for x in crabs] # because it could be either one.
+	return min([sum(fuel1), sum(fuel2)]) # just take the lesser of the two.
 
 print(part2(crabs))