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# -*- coding: utf-8 -*-
from abc import ABC
from copy import copy
from typing import Tuple, Iterator, List, Set
from aoc import BaseAssignment
from aoc.datastructures import Coordinate
class Assignment(BaseAssignment, ABC):
rope_length = NotImplemented
def parse_line(self, item: str) -> Tuple[str, int]:
direction, amount = item.split(" ")
return direction, int(amount)
def move(self, direction: str, amount: int):
pass
@staticmethod
def next_head(head: Coordinate, direction: str) -> Coordinate:
match direction:
case "R":
return head + Coordinate(1, 0)
case "L":
return head + Coordinate(-1, 0)
case "U":
return head + Coordinate(0, 1)
case "D":
return head + Coordinate(0, -1)
@staticmethod
def next_knot(head: Coordinate, tail: Coordinate) -> Coordinate:
delta = head - tail
if abs(delta.x) < 2 and abs(delta.y) < 2:
return tail
elif abs(delta.x) > 1 and delta.y == 0:
return tail + Coordinate(
delta.x - delta.polarity_x,
0,
)
elif abs(delta.x) > 1 and abs(delta.y) == 1:
return tail + Coordinate(delta.x - delta.polarity_x, delta.y)
elif abs(delta.y) > 1 and delta.x == 0:
return tail + Coordinate(
0,
delta.y - delta.polarity_y,
)
elif abs(delta.y) > 1 and abs(delta.x) == 1:
return tail + Coordinate(
delta.x,
delta.y - delta.polarity_y,
)
elif abs(delta.x) > 1 and abs(delta.y) > 1:
return tail + Coordinate(
delta.x - delta.polarity_x, delta.y - delta.polarity_y
)
def tail_positions(self, input: Iterator[str], length: int) -> Iterator[Coordinate]:
knots = [Coordinate(0, 0) for _ in range(length)]
for line in input:
direction, amount = self.parse_line(line)
for _ in range(amount):
for index in range(length):
if index == 0:
knots[0] = self.next_head(knots[0], direction)
continue
knots[index] = self.next_knot(knots[index - 1], knots[index])
yield knots[length - 1]
def unique_tail_positions(
self, input: Iterator[str], length: int
) -> Set[Coordinate]:
unique_tail_positions = set()
for position in self.tail_positions(input, length):
unique_tail_positions.add(copy(position))
return unique_tail_positions
def visualize(self, width: range, height: range, positions: Set[Coordinate]):
rows = []
for y in height:
items = []
for x in width:
if x == 0 and y == 0:
items.append("s")
elif Coordinate(x, y) in positions:
items.append("#")
else:
items.append(".")
rows.append(items)
return "\n".join(["".join(row) for row in reversed(rows)])
def run(self, input: Iterator) -> int:
unique_positions = self.unique_tail_positions(input, length=self.rope_length)
return len(unique_positions)
class AssignmentOne(Assignment):
example_result = 13
rope_length = 2
class AssignmentTwo(Assignment):
example_result = 36
rope_length = 10
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