advent-of-code-2k21/day3/day3.py
2021-12-06 18:28:08 +01:00

68 lines
1.8 KiB
Python

def calculate_gamma(inp):
gamma_rate = [0] * len(inp[0])
for line in inp:
for index, char in enumerate(line):
gamma_rate[index] += int(char)
gamma_rate = [0 if x < len(inp) // 2 else 1 for x in gamma_rate]
return gamma_rate
def part1(inp):
gamma = calculate_gamma(inp)
epsilon = [0 if x == 1 else 1 for x in gamma]
# power consumption = dec(gamma_rate) * dec(epsilon_rate)
power = int("".join(str(x) for x in gamma), 2) * int("".join(str(x) for x in epsilon), 2)
print("Part 1, power consumption : ", power)
def calculate_most_common(inp, pos):
sum = 0
for line in inp:
sum += int(line[pos])
return 0 if sum < len(inp) // 2 else 1
def filter_oxygen(inp, pos, most_common):
result = []
for line in inp:
if int(line[pos]) == most_common:
result.append(line)
return result
def oxygen_rating(inp):
result = inp[:]
for pos in range(len(inp[0])):
most_common = calculate_most_common(result, pos)
result = filter_oxygen(result, pos, most_common)
if len(result) == 1:
return result
def co2_rating(inp):
result = inp[:]
for pos in range(len(inp[0])):
least_common = 1 - calculate_most_common(result, pos)
result = filter_oxygen(result, pos, least_common)
if len(result) == 1:
return result
def part2(inp):
oxygen = oxygen_rating(inp)
co2 = co2_rating(inp)
res = int("".join(str(x) for x in oxygen), 2) * int("".join(str(x) for x in co2), 2)
print(f"Part 2 : {res}")
def main(input_file):
with open(input_file) as f:
entries = [x.rstrip() for x in f.readlines()]
part1(entries)
part2(entries)
if __name__ == "__main__":
main("input.txt")