adventofcode2024/day02-2.py

import logging

from itertools import pairwise
from sys import stdout

logger = logging.Logger(__name__)
logger_2 = logging.Logger(f"{__name__}_2")
formatter = logging.Formatter('[%(asctime)s][%(levelname)s] %(message)s')
sh = logging.StreamHandler(stdout)
sh.setLevel(logging.INFO)
sh.setFormatter(formatter)
fh = logging.FileHandler("./day02-2.log", mode="w", encoding="utf-8")
fh_2 = logging.FileHandler("./day02-2_round2.log", mode="w", encoding="utf-8")
fh.setLevel(logging.DEBUG)
fh.setFormatter(formatter)
fh_2.setLevel(logging.DEBUG)
fh_2.setFormatter(formatter)
logger.addHandler(sh)
logger.addHandler(fh)
logger_2.addHandler(fh_2)

# So, a report only counts as safe if both of the following are true:

#     The levels are either all increasing or all decreasing.
#     Any two adjacent levels differ by at least one and at most three.

# The Problem Dampener is a reactor-mounted module that lets the reactor 
# safety systems tolerate a single bad level in what would otherwise be a 
# safe report. It's like the bad level never happened!

# Now, the same rules apply as before, except if removing a single level 
# from an unsafe report would make it safe, the report instead counts as safe.

def report(msg, i=0, spotter=20, use_2=False):
    if i % spotter == 0:
        logger.info(msg)
    else:
        logger.debug(msg)
    if use_2:
        logger_2.debug(msg)

def test_line(line):
    pw_l = list(pairwise(line))
    raw_distances = [(y-x) for x,y in pw_l]
    abs_distances = [abs(x) for x in raw_distances]
    # -1 if the pair is going from high to low
    # 1 if the pair is going from low to high
    # 0 if the pair is equal
    directions = [-1 if x > y else (0 if x == y else 1) for x,y in pw_l]
    pure_ascending = all([d > 0 for d in directions])
    pure_descending = all([d < 0 for d in directions])
    pure_and_close = (pure_ascending or pure_descending) and all([1 <= d <= 3 for d in abs_distances])
    report(f"""Line {line}: 
    Pairs: {pw_l}
    Raw distances: {raw_distances}
    Absolute distances: {abs_distances}
    Directions: {directions}
    Pure ascending: {pure_ascending}
    Pure descending: {pure_descending}
    Pure and close: {pure_and_close}""", spotter=100, use_2=True)
    return {
        "Pairwise": pw_l, 
        "Raw distances": raw_distances, 
        "Absolute distances": abs_distances,
        "Directions": directions,
        "Pure ascending": pure_ascending,
        "Pure descending": pure_descending,
        "Pure and close": pure_and_close
    }
    
def main():
    with open("input02.txt", "r", encoding="utf-8") as f:
        lines = [list(map(int,l.split(" "))) for l in f.readlines()]

    line_stats = []
    safe_lines = 0
    for i, line in enumerate(lines):
        base_stats = test_line(line)
        line_stats.append(base_stats)
        if base_stats["Pure and close"]:
            safe_lines += 1
            continue
        break_out = False
        j = 0
        while not break_out and j < len(line):
            new_line = line[:j] + line[j+1:]
            report(f"Checking variant of line {line}: {new_line}")
            nl_stats = test_line(new_line)
            if nl_stats["Pure and close"]:
                safe_lines += 1
                break_out = True
                continue
            j += 1



    report(f"Number of safe lines: {safe_lines}")

if __name__ == "__main__":
    main()