Advent of Code 2021. Day 10 Python solution

with open("2021_day13_input.txt", "r", encoding="utf-8") as ifile:
    dots, instructions = map(str.splitlines, ifile.read().split("\n\n"))

dot_dict = dict(zip((dots := [(int((x := line.split(","))[0]), int(x[1])) for line in dots]), [True]*len(dots)))
instructions = [((x := line.split()[2].split("="))[0], int(x[1])) for line in instructions]
max_x, max_y = max([k[0] for k in dot_dict.keys()]), max([k[1] for k in dot_dict.keys()])


def fold_vertically(after_line, dot_dict):
    for y_add in range(1, max_y-after_line+1):
        for x in range(max_x+1):
            if (x, after_line+y_add, ) in dot_dict:
                dot_dict.pop((x, after_line+y_add, ))
                dot_dict[(x, after_line-y_add, )] = True


def fold_horizontally(after_column, dot_dict):
    for x_add in range(1, max_x-after_column+1):
        for y in range(max_y+1):
            if (after_column+x_add, y,) in dot_dict:
                dot_dict.pop((after_column+x_add, y,))
                dot_dict[(after_column-x_add, y,)] = True


def print_doc_dict(dot_dict):
    _max_x, _max_y = max([k[0] for k in dot_dict.keys()]), max([k[1] for k in dot_dict.keys()])
    for y in range(_max_y+1):
        line = ""
        for x in range(max_x+1):
            if (x, y,) in dot_dict:
                line += "X"
            else:
                line += "."
        print(line)


for pos, instruction in enumerate(instructions):
    match instruction[0]:
        case "x":
            fold_horizontally(instruction[1], dot_dict)
        case "y":
            fold_vertically(instruction[1], dot_dict)
    if pos == 0:
        print("Nr of dots after the first fold: {}".format(len(dot_dict)))

print_doc_dict(dot_dict)