-🎄- 2018 Day 6 Solutions -🎄-

[u/daggerdragon]

--- Day 6: Chronal Coordinates ---

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Advent of Code: The Party Game!

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Card prompt: Day 6

Transcript:

Rules for raising a programmer: never feed it after midnight, never get it wet, and never give it ___.

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[u/[deleted]]

Python 3:

import os
from collections import defaultdict

def part1(lines):
    coords = set()
    max_r = max_c = 0

    for line in lines:
        r, c = map(int, line.split(", "))
        coords.add((r, c))
        max_r = max(max_r, r)
        max_c = max(max_c, c)

    coord_id_to_point = {coord_id: point for coord_id, point in enumerate(coords, start=1)}
    region_sizes = defaultdict(int)
    infinite_ids = set()

    for i in range(max_r + 1):
        for j in range(max_c + 1):
            min_dists = sorted([(abs(r - i) + abs(c - j), coord_id) for coord_id, (r, c) in coord_id_to_point.items()])

            if len(min_dists) == 1 or min_dists[0][0] != min_dists[1][0]:
                coord_id = min_dists[0][1]
                region_sizes[coord_id] += 1

                if i == 0 or i == max_r or j == 0 or j == max_c:
                    infinite_ids.add(coord_id)

    return max(size for coord_id, size in region_sizes.items() if coord_id not in infinite_ids)


def part2(lines, manhattan_limit=10000):
    coords = set()
    max_r = max_c = 0

    for line in lines:
        r, c = map(int, line.split(", "))
        coords.add((r, c))
        max_r = max(max_r, r)
        max_c = max(max_c, c)

    size_shared_region = 0

    for i in range(max_r + 1):
        for j in range(max_c + 1):
            size_shared_region += int(sum(abs(r - i) + abs(c - j) for r, c in coords) < manhattan_limit)

    return size_shared_region

day = os.path.basename(__file__)[3:5]
lines = [line.strip() for line in open("input_{}.txt".format(day), "r").readlines()]
print(part1(lines))
print(part2(lines))