Advent Of Code 2015: Day 6

The Challenge

--- Day 6: Probably a Fire Hazard ---

Because your neighbors keep defeating you in the holiday house decorating contest year after year, you've decided to deploy one million lights in a 1000x1000 grid.

Furthermore, because you've been especially nice this year, Santa has mailed you instructions on how to display the ideal lighting configuration.

Lights in your grid are numbered from 0 to 999 in each direction; the lights at each corner are at 0,0, 0,999, 999,999, and 999,0. The instructions include whether to turn on, turn off, or toggle various inclusive ranges given as coordinate pairs. Each coordinate pair represents opposite corners of a rectangle, inclusive; a coordinate pair like 0,0 through 2,2 therefore refers to 9 lights in a 3x3 square. The lights all start turned off.

To defeat your neighbors this year, all you have to do is set up your lights by doing the instructions Santa sent you in order.

For example:

turn on 0,0 through 999,999 would turn on (or leave on) every light.
toggle 0,0 through 999,0 would toggle the first line of 1000 lights, turning off the ones that were on, and turning on the ones that were off.
turn off 499,499 through 500,500 would turn off (or leave off) the middle four lights.
After following the instructions, how many lights are lit?

Your puzzle answer was 569999.

--- Part Two ---

You just finish implementing your winning light pattern when you realize you mistranslated Santa's message from Ancient Nordic Elvish.

The light grid you bought actually has individual brightness controls; each light can have a brightness of zero or more. The lights all start at zero.

The phrase turn on actually means that you should increase the brightness of those lights by 1.

The phrase turn off actually means that you should decrease the brightness of those lights by 1, to a minimum of zero.

The phrase toggle actually means that you should increase the brightness of those lights by 2.

What is the total brightness of all lights combined after following Santa's instructions?

For example:

turn on 0,0 through 0,0 would increase the total brightness by 1.
toggle 0,0 through 999,999 would increase the total brightness by 2000000.
Your puzzle answer was 17836115.

Solution

I split up the solutions for part 1 and part 2. Was almost tempted to go for a numpy and scipy sparse matrix solution but a 1000x1000 matrix is small enough for a dense matrix.

Part 1

# Day 6 - Part 1
import re

lightMatrix = [[False for x in range(1000)] for x in range(1000)] 
lightOnCounter = 0

with open('input.txt') as f:
  for line in f:
    # Match command
    res = re.search(r'(turn on|turn off|toggle)\s*(\d*?),(\d*?)\s*through\s(\d*?),(\d*)', line)
    command, lower_X, lower_Y, upper_X, upper_Y =  res.group(1), int(res.group(2)), int(res.group(3)), int(res.group(4)), int(res.group(5))
    
    # Perform actions
    toggle = False
    
    if command == 'turn off':
      data = False
    elif command == 'turn on':
      data = True
    elif command == 'toggle':
      toggle = True
      
    # Apply action
    for x_val in xrange (lower_X, upper_X + 1):
      for y_val in xrange (lower_Y, upper_Y + 1):
        if toggle:
          lightMatrix[x_val][y_val] = not lightMatrix[x_val][y_val]
        else:
          lightMatrix[x_val][y_val] = data
        
# Get all true lights
for i in lightMatrix:
  for isLightOn in i:
    lightOnCounter += isLightOn #bool to int implicitly

# answer
print "Total number of lights that are on:", lightOnCounter

Part 2

# Day 6 - Part 2
import re

lightMatrix = [[0 for x in range(1000)] for x in range(1000)] 
brightnessCounter = 0

with open('input.txt') as f:
  for line in f:
    # Match command
    res = re.search(r'(turn on|turn off|toggle)\s*(\d*?),(\d*?)\s*through\s(\d*?),(\d*)', line)
    command, lower_X, lower_Y, upper_X, upper_Y =  res.group(1), int(res.group(2)), int(res.group(3)), int(res.group(4)), int(res.group(5))
    
    # Perform actions
    if command == 'turn off':
      data = -1
    elif command == 'turn on':
      data = 1
    elif command == 'toggle':
      data = 2
      
    # Apply action
    for x_val in xrange (lower_X, upper_X + 1):
      for y_val in xrange (lower_Y, upper_Y + 1):
        lightMatrix[x_val][y_val] += data if lightMatrix[x_val][y_val] + data >= 0 else 0
        
# Get brightness level
for i in lightMatrix:
  for brightness in i:
    brightnessCounter += brightness

# answer
print "Total brightness level is:", brightnessCounter