cleanup and catchup

This commit is contained in:
a 2021-12-07 23:41:35 -06:00
parent 10875cb375
commit 700245aa3a
2 changed files with 77 additions and 26 deletions

View file

@ -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)

View file

@ -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))