advent-of-code/2018/d11/ex2/ex2.py

71 lines
2.1 KiB
Python
Executable file

#!/usr/bin/env python
import itertools
import sys
from typing import NamedTuple
class Point(NamedTuple):
x: int
y: int
def solve(input: str) -> str:
def cell_power(cell: Point, serial: int) -> int:
rack_id = cell.x + 10
power = rack_id * cell.y
power += serial
power *= rack_id
return ((power // 100) % 10) - 5
def summed_area(power_map: dict[Point, int]) -> dict[Point, int]:
res: dict[Point, int] = {}
for p in map(Point._make, itertools.product(range(1, 300 + 1), repeat=2)):
res[p] = (
power_map[p]
+ res.get(Point(p.x - 1, p.y), 0)
+ res.get(Point(p.x, p.y - 1), 0)
- res.get(Point(p.x - 1, p.y - 1), 0)
)
assert len(res) == len(power_map) # Sanity check
return res
def sum_square(top_left: Point, size: int, summed_table: dict[Point, int]) -> int:
bot_right = Point(top_left.x + size - 1, top_left.y + size - 1)
return (
summed_table[bot_right]
- summed_table.get(Point(top_left.x - 1, bot_right.y), 0)
- summed_table.get(Point(bot_right.x, top_left.y - 1), 0)
+ summed_table.get(Point(top_left.x - 1, top_left.y - 1), 0)
)
def best_square(summed_table: dict[Point, int]) -> tuple[Point, int]:
return max(
(
(top_left, size)
for size in range(1, 300 + 1)
for top_left in map(
Point._make, itertools.product(range(1, 300 + 1 - size), repeat=2)
)
),
key=lambda t: sum_square(t[0], t[1], summed_table),
)
serial = int(input)
power_map = {
p: cell_power(p, serial)
for p in map(Point._make, itertools.product(range(1, 300 + 1), repeat=2))
}
summed_table = summed_area(power_map)
top_left, size = best_square(summed_table)
return f"{top_left.x},{top_left.y},{size}"
def main() -> None:
input = sys.stdin.read()
print(solve(input))
if __name__ == "__main__":
main()