Advent of Code 2024, day 08

AdventOfCode2024.Day08.py

import sys
from itertools import combinations

sys.setrecursionlimit(10**6)

with open("./data/input08.txt") as inputFile:
    input = inputFile.read().splitlines()

antennas = {}
for r in range(len(input)):
    for c in range(len(input[r])):
        if input[r][c] != '.':
            antenna_type = input[r][c]
            if not(antenna_type in antennas):
                antennas[antenna_type] = []
            antennas[antenna_type].append((r,c))

antenna_pairs = {}
for antenna_type in antennas.keys():
    pairs = list(combinations(antennas[antenna_type], 2))
    antenna_pairs[antenna_type] = pairs

# Part 1:

antinodes = set()
for antenna_type in antenna_pairs.keys():
    pairs = antenna_pairs[antenna_type]
    for pair in pairs:
        (a1, a2) = pair
        (r1, c1) = a1
        (r2, c2) = a2
        nr1 = min(r1, r2) - abs(r1 - r2)
        nc1 = 0
        if r1 < r2:
            if c1 < c2: nc1 = c1 - abs(c1 - c2) 
            elif c1 > c2: nc1 = c1 + abs(c1 - c2)
            else: nc1 = c1
        elif r1 > r2:
            if c1 < c2: nc1 = c1 + abs(c1 - c2) 
            elif c1 > c2: nc1 = c1 - abs(c1 - c2)
            else: nc1 = c1
        else:
            nc1 = min(c1, c2) - abs(c1 - c2)
        nr2 = max(r1, r2) + abs(r1 - r2)
        nc2 = 0
        if nc1 < min(c1, c2): 
            nc2 = max(c1, c2) + abs(c1 - c2)
        else:
            nc2 = min(c1, c2) - abs(c1 - c2)
        if nr1 in range(len(input)) and nc1 in range(len(input[0])):
            antinodes.add((nr1, nc1))
        if nr2 in range(len(input)) and nc2 in range(len(input[0])):
            antinodes.add((nr2, nc2))

res = len(antinodes)
print(res)

# Part 2:

antinodes = set()
for antenna_type in antenna_pairs.keys():
    pairs = antenna_pairs[antenna_type]
    for pair in pairs:
        (a1, a2) = pair
        r1 = a1[0] if a1[0] < a2[0] else a2[0] if a1[0] > a2[0] else a1[0]
        c1 = a1[1] if a1[0] < a2[0] else a2[1] if a1[0] > a2[0] else a1[1]
        r2 = a2[0] if a1[0] < a2[0] else a1[0] if a1[0] > a2[0] else a2[0]
        c2 = a2[1] if a1[0] < a2[0] else a1[1] if a1[0] > a2[0] else a2[1]
        if r1 == r2:
            for c in range(len(input[0])):
                antinodes.add((r1, c))
        else:
            for r in range(len(input)):
                if r == r1: antinodes.add((r1, c1))
                elif r == r2: antinodes.add((r2, c2))
                elif (abs(r - r1) * abs(c2 - c1)) % abs(r2 - r1) == 0:
                    diff = (abs(r - r1) * abs(c2 - c1)) // (r2 - r1)
                    if r < r1 and c1 < c2 or r > r1 and c1 > c2:
                        c = c1 - diff
                    else:
                        c = c1 + diff
                    if r in range(len(input)) and c in range(len(input[0])):
                        antinodes.add((r, c))
                else:
                    d = abs(c2 - c1) % abs(r2 - r1)

res = len(antinodes)
print(res)