mirror of
https://github.com/bertptrs/adventofcode.git
synced 2025-12-25 21:00:31 +01:00
83 lines
1.7 KiB
Python
83 lines
1.7 KiB
Python
import itertools
|
|
|
|
import numpy
|
|
|
|
from . import SeparateRunner
|
|
|
|
DIRECTIONS = [
|
|
(-1, 0),
|
|
(1, 0),
|
|
(0, -1),
|
|
(0, 1),
|
|
]
|
|
|
|
CHEATS = [
|
|
(-2, 0),
|
|
(2, 0),
|
|
(0, -2),
|
|
(0, 2),
|
|
]
|
|
|
|
|
|
def parse_path(input: str) -> dict[tuple[int, int], int]:
|
|
grid = numpy.array(list(map(list, input.strip().split("\n"))))
|
|
|
|
ys, xs = numpy.nonzero(grid == "S")
|
|
sx, sy = int(xs[0]), int(ys[0])
|
|
|
|
nx, ny = sx, sy
|
|
|
|
path = {
|
|
(sx, sy): 0,
|
|
}
|
|
|
|
while grid[ny, nx] != "E":
|
|
x, y = nx, ny
|
|
|
|
for dx, dy in DIRECTIONS:
|
|
if grid[y + dy, x + dx] == "#" or (x + dx, y + dy) in path:
|
|
continue
|
|
nx = x + dx
|
|
ny = y + dy
|
|
break
|
|
|
|
path[nx, ny] = len(path)
|
|
return path
|
|
|
|
|
|
def get_savings(a: tuple[tuple[int, int], int], b: tuple[tuple[int, int], int]) -> int:
|
|
(ax, ay), ad = a
|
|
(bx, by), bd = b
|
|
|
|
dist = abs(bx - ax) + abs(by - ay)
|
|
if dist <= 20:
|
|
return bd - ad - dist
|
|
else:
|
|
return 0
|
|
|
|
|
|
class DayRunner(SeparateRunner):
|
|
@classmethod
|
|
def part1(cls, input: str, limit: int = 100) -> int:
|
|
path = parse_path(input)
|
|
|
|
total = 0
|
|
|
|
for (px, py), dist in path.items():
|
|
for dx, dy in CHEATS:
|
|
if (other := path.get((px + dx, py + dy))) is not None:
|
|
savings = dist - other - 2
|
|
if savings >= limit:
|
|
total += 1
|
|
|
|
return total
|
|
|
|
@classmethod
|
|
def part2(cls, input: str, limit: int = 100) -> int:
|
|
path = parse_path(input)
|
|
|
|
return sum(
|
|
get_savings(a, b) >= limit
|
|
for a, b in itertools.combinations(path.items(), 2)
|
|
)
|