advent-of-code/2020/day12_navigation.py

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2020-12-12 19:13:24 +01:00
import enum
import functools
from typing import List
def main(filename: str, expected_part_1: int = None, expected_part_2: int = None):
print(f"\n+ Running on {filename}")
with open(filename) as f:
instructions = f.read().strip().split("\n")
counter_part_1 = solve_part_1(instructions)
counter_part_2 = 0
print(f"1. Found {counter_part_1}")
if expected_part_1:
assert expected_part_1 == counter_part_1
print(f"2. Found {counter_part_2}")
if expected_part_2:
assert expected_part_2 == counter_part_2
def solve_part_1(instructions: List[str]):
ship = Ship()
ship.apply_instructions(instructions)
return ship.distance_from_origin
class Ship:
def __init__(self):
self.facing = Direction.EAST
self.movements = {
Direction.NORTH: 0,
Direction.SOUTH: 0,
Direction.EAST: 0,
Direction.WEST: 0,
}
def apply_instructions(self, instructions):
for instruction in instructions:
self.apply_instruction(instruction)
@property
def distance_from_origin(self):
return abs(
self.movements[Direction.NORTH] - self.movements[Direction.SOUTH]
) + abs(self.movements[Direction.EAST] - self.movements[Direction.WEST])
def apply_instruction(self, instruction):
letter = instruction[0]
value = int(instruction[1:])
if letter in Direction.values():
direction = Direction(letter)
self.move(direction, value)
elif letter == "F":
self.move(self.facing, value)
elif letter in ["R", "L"]:
if letter == "L":
value = -value
self.facing = self.facing.turn(value)
def move(self, direction: "Direction", value: int):
self.movements[direction] += value
class Direction(enum.Enum):
NORTH = "N"
SOUTH = "S"
EAST = "E"
WEST = "W"
@staticmethod
@functools.lru_cache(maxsize=1)
def values():
return {e.value for e in Direction}
def turn(self, angle):
if angle == 0:
return self
if self == Direction.NORTH:
if angle > 0:
return Direction.EAST.turn(angle - 90)
else:
return Direction.WEST.turn(angle + 90)
if self == Direction.SOUTH:
if angle > 0:
return Direction.WEST.turn(angle - 90)
else:
return Direction.EAST.turn(angle + 90)
if self == Direction.EAST:
if angle > 0:
return Direction.SOUTH.turn(angle - 90)
else:
return Direction.NORTH.turn(angle + 90)
if self == Direction.WEST:
if angle > 0:
return Direction.NORTH.turn(angle - 90)
else:
return Direction.SOUTH.turn(angle + 90)
if __name__ == "__main__":
main("inputs/day12-test1", 25)
main("inputs/day12")