advent-of-code-2019/day10.py

#!/usr/bin/env python3

from math import gcd
from fractions import Fraction
from itertools import product
from functools import total_ordering
from collections import defaultdict

ASTEROID = '#'

def zrange(x, y, step):
    if x == y == step == 0:
        def yzero():
            while True:
                yield 0
        return yzero()
    return range(x, y, step)

def angle(v):
        if v.x == 0:
            return (2 * int(v.y > 0), 0)
        halve = 1 if v.x > 0 else 3
        return (halve, Fraction(v.y, v.x))

def rebase(base, vectors):
    return (v - base for v in vectors if v != base)

@total_ordering
class Vector:
    def __init__(self, x, y):
        self.x = x
        self.y = y
    def __add__(self, other):
        return Vector(self.x + other.x, self.y + other.y)
    def __sub__(self, other):
        return self + Vector(-other.x, -other.y)
    def __eq__(self, other):
        return self.x == other.x and self.y == other.y
    def __lt__(self, other):
        return (self.x**2 + self.y**2) < (other.x**2 + other.y**2)
    def __str__(self):
        return str((self.x, self.y))
    def __repr__(self):
        return str(self)

class Map:
    def __init__(self, map):
        self.map = map

    def __getitem__(self, v):
        return self.map[v.y][v.x]

    def __str__(self):
        return '\n'.join(self.map)

    def is_asteroid(self, v):
        return self[v] == ASTEROID

    def vectors(self):
        X, Y = len(self.map[0]), len(self.map)
        return (Vector(x, y) for x, y in product(range(X), range(Y)))

    def asteroid_vectors(self):
        return filter(lambda v: self.is_asteroid(v), self.vectors())

    def num_in_sight(self, v):
        vs = rebase(v, self.asteroid_vectors())
        return len(set(map(angle, vs)))

    def best(self):
        return max((self.num_in_sight(v), v) for v in self.asteroid_vectors())

    def vaporize_seq(self, base):
        vs = rebase(base, self.asteroid_vectors())
        angles = defaultdict(list)
        for v in vs:
            angles[angle(v)].append(v)
        for ang in angles.keys():
            angles[ang].sort()
        r = []
        for i in range(max(map(len, angles.values()))):
            r += [angles[ang][i] + base
                  for ang in sorted(angles.keys()) if i < len(angles[ang])]
        return r

def preproc(puzzle_input):
    asteroid_map = Map(puzzle_input.split())
    score, asteroid = asteroid_map.best()
    return asteroid_map, asteroid, score

def partI(packed):
    _, _, score = packed
    return score

def partII(packed):
    asteroid_map, asteroid, _ = packed
    v = asteroid_map.vaporize_seq(asteroid)[199]
    return 100*v.x + v.y

from main import Tests

tests = Tests()

map1 = \
""".#..#
.....
#####
....#
...##"""

map2 = \
"""#.#...#.#.
.###....#.
.#....#...
##.#.#.#.#
....#.#.#.
.##..###.#
..#...##..
..##....##
......#...
.####.###.
"""

map3 = \
""".#..##.###...#######
##.############..##.
.#.######.########.#
.###.#######.####.#.
#####.##.#.##.###.##
..#####..#.#########
####################
#.####....###.#.#.##
##.#################
#####.##.###..####..
..######..##.#######
####.##.####...##..#
.#####..#.######.###
##...#.##########...
#.##########.#######
.####.#.###.###.#.##
....##.##.###..#####
.#.#.###########.###
#.#.#.#####.####.###
###.##.####.##.#..##
"""

tests.add(map1, partI=8)
tests.add(map2, partI=35)
tests.add(map3, partI=210, partII=802)