advent3_part2.py

from typing import List

input_trees = []
with open("files/advent3_input.txt", "r") as in_f:
    for line in in_f.readlines():
        input_trees.append(line.strip())

class Spot:
    row: int
    col: int

    def __init__(self, row: int, col: int):
        self.row = row
        self.col = col


class TreeGrid:
    base_grid: List[str]

    def __init__(self, tree_grid: List[str]):
        self.base_grid = tree_grid

    def get_grid_height(self):
        return len(self.base_grid)

    def get_coord(self, spot: Spot) -> str:
        assert spot.row <= len(self.base_grid), "row out of bounds"
        col = spot.col % len(self.base_grid[0])
        return self.base_grid[spot.row][col]


def calculate_trees_hit_for_slope(right: int, down: int):
    trees_hit = 0
    tree_grid = TreeGrid(input_trees)
    spot = Spot(0, 0)
    while True:
        if spot.row >= tree_grid.get_grid_height():
            break
        if tree_grid.get_coord(spot) == "#":
            trees_hit += 1
        spot = Spot(spot.row + down, spot.col + right)
    return trees_hit


# Right 1, down 1.
# Right 3, down 1.
# Right 5, down 1.
# Right 7, down 1.
# Right 1, down 2.
slopes = [
    (1, 1),
    (3, 1),
    (5, 1),
    (7, 1),
    (1, 2)
]

mult = 1
for slope in slopes:
    mult *= calculate_trees_hit_for_slope(slope[0], slope[1])
print(mult)