08.py

from pathlib import Path


def is_visible_left(x: int, y: int, grid: list[list[int]]) -> bool:
    height = grid[y][x]
    for x_index in range(x):
        if grid[y][x_index] >= height:
            return False
    return True


def is_visible_right(x: int, y: int, grid: list[list[int]]) -> bool:
    height = grid[y][x]
    for x_index in range(x+1, len(grid[y])):
        if grid[y][x_index] >= height:
            return False
    return True


def is_visible_up(x: int, y: int, grid: list[list[int]]) -> bool:
    height = grid[y][x]
    for y_index in range(y):
        if grid[y_index][x] >= height:
            return False
    return True


def is_visible_down(x: int, y: int, grid: list[list[int]]) -> bool:
    height = grid[y][x]
    for y_index in range(y+1, len(grid)):
        if grid[y_index][x] >= height:
            return False
    return True


def part_a(contents: str):
    grid = parse_to_grid(contents)

    result = len(grid) * 2
    result += len(grid[0]) * 2
    result -= 4

    for line_index, line in enumerate(grid[1:-1]):
        for character_index, character in enumerate(line[1:-1]):
            if is_visible_left(character_index+1, line_index+1, grid) or\
                    is_visible_right(character_index+1, line_index+1, grid) or \
                    is_visible_up(character_index+1, line_index+1, grid) or\
                    is_visible_down(character_index+1, line_index+1, grid):
                result += 1
    return result


def calculate_scenic_score(x: int, y: int, grid: list[list[int]]) -> int:
    height = grid[y][x]
    num_visible_left = 0
    num_visible_right = 0
    num_visible_up = 0
    num_visible_down = 0

    for x_index in range(x-1, -1, -1):
        num_visible_left += 1
        if grid[y][x_index] >= height:
            break

    for x_index in range(x+1, len(grid[0])):
        num_visible_right += 1
        if grid[y][x_index] >= height:
            break

    for y_index in range(y - 1, -1, -1):
        num_visible_up += 1
        if grid[y_index][x] >= height:
            break

    for y_index in range(y + 1, len(grid)):
        num_visible_down += 1
        if grid[y_index][x] >= height:
            break

    return num_visible_left * num_visible_right * num_visible_down * num_visible_up


def part_b(contents: str):
    grid = parse_to_grid(contents)

    result = 0
    for line_index, line in enumerate(grid[1:-1]):
        for character_index, character in enumerate(line[1:-1]):
            result = max(result, calculate_scenic_score(character_index+1, line_index+1, grid))

    return result


def parse_to_grid(contents: str) -> list[list[int]]:
    lines = contents.split("\n")
    lines = [list(line) for line in lines]
    for line_index in range(len(lines)):
        for character_index in range(len(lines[line_index])):
            lines[line_index][character_index] = int(lines[line_index][character_index])
    return lines


def main():
    contents = Path("08_input.txt").read_text().strip()
    print(part_a(contents))
    print(part_b(contents))


if __name__ == "__main__":
    main()