Mikaël Capelle ce315b8778 Refactor code for API (#3)
Co-authored-by: Mikael CAPELLE <mikael.capelle@thalesaleniaspace.com>
Co-authored-by: Mikaël Capelle <capelle.mikael@gmail.com>
Reviewed-on: #3
2024-12-08 13:06:41 +00:00

123 lines
3.5 KiB
Python

import itertools as it
from typing import Any, Iterator, TypeAlias
from ..base import BaseSolver
NodeType: TypeAlias = tuple[tuple[int, int], tuple[int, int]]
EdgesType: TypeAlias = dict[NodeType, tuple[NodeType, set[tuple[int, int]]]]
ROTATE = {(-1, 0): (0, 1), (0, 1): (1, 0), (1, 0): (0, -1), (0, -1): (-1, 0)}
START_NODE: NodeType = ((-2, -2), (-1, 0))
FINAL_POS: tuple[int, int] = (-1, -1)
def move(
lines: list[str], pos: tuple[int, int], dir: tuple[int, int]
) -> tuple[tuple[int, int] | None, set[tuple[int, int]]]:
n_rows, n_cols = len(lines), len(lines[0])
row, col = pos
marked: set[tuple[int, int]] = set()
final_pos: tuple[int, int] | None = None
while True:
marked.add((row, col))
if not (0 <= row + dir[0] < n_rows and 0 <= col + dir[1] < n_cols):
final_pos = None
break
if lines[row + dir[0]][col + dir[1]] != ".":
final_pos = (row, col)
break
row += dir[0]
col += dir[1]
return final_pos, marked
def compute_graph(lines: list[str], start_node: NodeType):
n_rows, n_cols = len(lines), len(lines[0])
edges: EdgesType = {}
start_pos, start_dir = start_node
end_pos, marked = move(lines, start_pos, start_dir)
assert end_pos is not None
edges[START_NODE] = ((end_pos, start_dir), marked)
for row, col in it.product(range(n_rows), range(n_cols)):
if lines[row][col] != "#":
continue
for start_pos, start_dir in (
((row - 1, col), (1, 0)),
((row + 1, col), (-1, 0)),
((row, col - 1), (0, 1)),
((row, col + 1), (0, -1)),
):
if 0 <= start_pos[0] < n_rows and 0 <= start_pos[1] < n_cols:
end_pos, marked = move(lines, start_pos, ROTATE[start_dir])
edges[start_pos, start_dir] = (
(end_pos or FINAL_POS, ROTATE[start_dir]),
marked,
)
return edges
def is_loop(lines: list[str], edges: EdgesType, position: tuple[int, int]):
row, col = position
current_node = START_NODE
found: set[NodeType] = set()
while current_node[0] != FINAL_POS and current_node not in found:
found.add(current_node)
target_node, edge_marked = edges[current_node]
if (row, col) in edge_marked:
# need to break the edge
target_dir = target_node[1]
end_pos, _ = move(
lines, (row - target_dir[0], col - target_dir[1]), ROTATE[target_dir]
)
current_node = (end_pos or FINAL_POS, ROTATE[target_dir])
else:
current_node = target_node
return current_node in found
class Solver(BaseSolver):
def solve(self, input: str) -> Iterator[Any]:
# read lines
lines = input.splitlines()
# find and delete original position
start_pos = next(
(i, j)
for i, row in enumerate(lines)
for j, col in enumerate(row)
if col == "^"
)
lines[start_pos[0]] = lines[start_pos[0]].replace("^", ".")
# compute edges from the map
edges = compute_graph(lines, (start_pos, (-1, 0)))
# part 1
marked: set[tuple[int, int]] = set()
current_node = START_NODE
while current_node[0] != FINAL_POS:
current_node, current_marked = edges[current_node]
marked = marked.union(current_marked)
yield len(marked)
yield sum(is_loop(lines, edges, pos) for pos in marked if pos != start_pos)