advent_of_code/2021/3/3_2.py

#!/usr/bin/env python
# 2021 - Advent Of Code - 3 part2

import re

re_parse = re.compile(r'(\d)'*12)
MOST = 1
LEAST = 0


def freq_bits(buf, mode):
    count = [0] * 12
    co2_freq = [0] * 12
    oxy = [0] * 12
    for line in buf:
        m = re_parse.match(line)

        for i in range(12):
            if m.group(i+1) == '1':
                count[i] += 1

    for i in range(12):
        if count[i] >= len(buf) / 2:
            oxy[i] = 1
        else:
            oxy[i] = 0

    for i in range(12):
        if count[i] > len(buf) / 2:
            co2_freq[i] = 1
        else:
            co2_freq[i] = 0

    if mode == MOST:
        return oxy
    if mode == LEAST:
        co2_freq = [0 if x == 1 else 1 for x in oxy]
        return co2_freq

    return None


def filter_pos(line_buffer, position, value):
    for line in line_buffer:
        if line[position] == value:
            yield line


def filter_freq(buffer, freq_buf, mode):
    i = 0
    while i in range(12) and len(buffer) > 1:
        buffer = list(filter_pos(buffer, i, str(freq_buf[i])))
        freq_buf = freq_bits(buffer, mode)
        print(len(buffer))
        i += 1

    return buffer


line_buf = []
with open('input.txt', encoding="utf-8") as f:
    for input_line in f:
        line_buf.append(input_line)

gamma_count = freq_bits(line_buf, MOST)
gamma_bin = "".join([str(x) for x in gamma_count])
gamma = int(gamma_bin, 2)

epsilon_count = freq_bits(line_buf, LEAST)
epsilon_bin = "".join([str(x) for x in epsilon_count])
epsilon = int(epsilon_bin, 2)

print(f'gamma_bin   {gamma_bin}, gamma: {gamma}')
print(f'epsilon_bin {epsilon_bin}, epsilon: {epsilon}')

oxybuf = filter_freq(line_buf, gamma_count, MOST)
co2buf = filter_freq(line_buf, epsilon_count, LEAST)

oxygen = int(oxybuf[0].strip(), 2)
print(f'oxybuf: {oxybuf}, oxygen: {oxygen}')

co2 = int(co2buf[0].strip(), 2)
print(f'co2buf: {co2buf}, co2: {co2}')
print(f'life support: {oxygen}, {co2} => {oxygen * co2}')