day8.py

import io, re


def read_instructions(filename):
    file = io.open(filename)
    rect_pat = re.compile('rect (\d+)x(\d+)')
    row_pat = re.compile('rotate row y=(\d+) by (\d+)')
    col_pat = re.compile('rotate column x=(\d+) by (\d+)')
    instructions = []

    for line in file:
        rect_m = rect_pat.match(line)
        row_m = row_pat.match(line)
        col_m = col_pat.match(line)

        if rect_m:
            instructions.append(('rect', int(rect_m[1]), int(rect_m[2])))
        elif row_m:
            instructions.append(('row', int(row_m[1]), int(row_m[2])))
        elif col_m:
            instructions.append(('col', int(col_m[1]), int(col_m[2])))

    return instructions


def new_lcd():
    lcd = []
    for y in range(0, 6):
        lcd.append([])
        for x in range(0, 50):
            lcd[y].append(False)
    return lcd


def run_rect(lcd, w, h):
    for y in range(0, h):
        for x in range(0, w):
            lcd[y][x] = True


def run_row(lcd, row_num, shift):
    row = lcd[row_num]
    lcd[row_num] = row[len(row)-shift:] + row[0:len(row)-shift]


def run_col(lcd, col_num, shift):
    col = []
    for y in range(0, len(lcd)): col.append(lcd[y][col_num])
    col = col[len(col)-shift:] + col[0:len(col)-shift]
    for y in range(0, len(lcd)): lcd[y][col_num] = col[y]


def run_instructions(instructions):
    lcd = new_lcd()
    for inst, arg1, arg2 in instructions:
        if inst == 'rect': run_rect(lcd, arg1, arg2)
        elif inst == 'row': run_row(lcd, arg1, arg2)
        elif inst == 'col': run_col(lcd, arg1, arg2)
    return lcd


def count_pixels(lcd):
    count = 0
    for row in lcd:
        for pixel in row:
            if pixel: count+= 1
    return count


def print_lcd(lcd):
    for row in lcd:
        str = ''
        for pixel in row:
            if pixel: str += '#'
            else: str += '.'
        print(str)


finished_lcd = run_instructions(read_instructions('day8.txt'))

print('Part 1: %d' % count_pixels(finished_lcd))

print('Part 2:')
print_lcd(finished_lcd)