Sean McLemon | Advent of Code

2018-12-03 - No Matter How You Slice It

(original .ipynb)

import re

data = open("puzzle_input/day3.txt").readlines()

class Claim(object):
    def __init__(self, raw_input):
        parsed_input = re.search("^#(\d+) @ (\d+),(\d+): (\d+)x(\d+)$", raw_input)
        assert(len(parsed_input.groups()) == 5)
        
        claim_id = int(parsed_input.group(1))
        left_pad = int(parsed_input.group(2))
        top_pad = int(parsed_input.group(3))
        width = int(parsed_input.group(4))
        height = int(parsed_input.group(5))
        
        self.claim_id = claim_id
        self.left = left_pad
        self.top = top_pad
        self.width = width
        self.height = height
        self.overlaps = 0

    def has_overlap(self, other):
        return not(self.left > other.left + other.width
            or self.left + self.width < other.left
            or self.top > other.top + other.height
            or self.top + self.height < other.top)
    
def create_grid(width, height):
    grid = []
    for i in range(height + 1):
        grid.append([ 0 ] * width)
    return grid

claims = [ Claim(d) for d in data ]

# Part 1
# Counting how many square inches are covered by >1 claim. I basically just create a NxM grid
# of integers, loop through all claims point-by-point incrementing the value at each grid point

max_grid_x = max( [ claim.left + claim.width for claim in claims ] )
max_grid_y = max( [ claim.top + claim.height for claim in claims ] )

grid = create_grid(max_grid_x, max_grid_y)

for claim in claims:
    for x in range(claim.left, claim.left + claim.width):
        for y in range(claim.top, claim.top + claim.height):
            grid[x][y] += 1

overlaps = 0
for row in grid:
    for col in row:
        if col > 1:
            overlaps += 1
            
print("part one:", overlaps)

part one: 117505

# Part 2
# Luckily I mis-read the first question and implemented that nasty "has_overlap" function
# so just loop over the claims and stop when we find one

for i, claim in enumerate(claims):
    for other in claims[1 + i:]:
        if claim.has_overlap(other):
            claim.overlaps += 1
            other.overlaps += 1
        
isolated_claims = [ claim.claim_id for claim in claims if claim.overlaps == 0 ]

assert(len(isolated_claims) == 1)

print("part two:", isolated_claims[0])

part two: 1254