advent-of-code/2020/d12/ex2/ex2.py

70 lines
1.5 KiB
Python
Executable file

#!/usr/bin/env python
import sys
from dataclasses import dataclass
from typing import List, Tuple
Instruction = Tuple[str, int]
Position = Tuple[int, int]
@dataclass
class Ship:
pos: Position
rel_waypoint: Position
ORIENTATIONS = ["N", "W", "S", "E"]
MOVES = {
"N": (1, 0),
"W": (0, -1),
"S": (-1, 0),
"E": (0, 1),
}
def move_ship(pos: Ship, instr: Instruction) -> Ship:
if instr[0] == "L":
assert instr[1] % 90 == 0
turns = instr[1] // 90
x, y = pos.rel_waypoint
for __ in range(turns):
x, y = y, -x
return Ship(pos.pos, (x, y))
elif instr[0] == "R":
assert instr[1] % 90 == 0
turns = instr[1] // 90
x, y = pos.rel_waypoint
for __ in range(turns):
x, y = -y, x
return Ship(pos.pos, (x, y))
elif instr[0] == "F":
dx, dy = pos.rel_waypoint
x, y = pos.pos
x += dx * instr[1]
y += dy * instr[1]
return Ship((x, y), pos.rel_waypoint)
else:
dx, dy = MOVES[instr[0]]
x, y = pos.rel_waypoint
x += dx * instr[1]
y += dy * instr[1]
return Ship(pos.pos, (x, y))
def solve(raw: List[str]) -> int:
instructions = [(i[0], int(i[1:])) for i in raw]
ship = Ship((0, 0), (1, 10))
for i in instructions:
ship = move_ship(ship, i)
return sum(abs(c) for c in ship.pos)
def main() -> None:
input = [line.strip() for line in sys.stdin.readlines()]
print(solve(input))
if __name__ == "__main__":
main()