AOC 2018 - Day 3 - Python

aoc2018_day3.py

# Input for both parts

lines = [line.strip() for line in open('day3.txt')]
data = []
for line in lines:
    parts = line.split(' ')
    id = parts[0]
    x, y = [int(x) for x in parts[2].rstrip(':').split(',')]
    w, h = [int(x) for x in parts[3].split('x')]
    data.append([id, x, y, w, h])

# Part 1

fabric = {}
for d in data:
    _, x, y, w, h = [value for value in d]
    for i in range(x, x + w):
        for j in range(y, y + h):
            fabric[(i, j)] = fabric[(i, j)] + 1 if (i, j) in fabric else 1
print(sum([1 for numDupes in fabric.values() if numDupes > 1]))

# Part 2 (geometry based)

fabric = {}
i = 0
skip = []
while i < len(data):
    aid, ax, ay, aw, ah = data[i]
    j = -1
    separated = True
    while separated and j + 1 < len(data):
        j += 1
        if i == j:
            j += 1
            continue
        bid, bx, by, bw, bh = data[j]
        separated = ax >= bx + bw or ax + aw <= bx or ay >= by + bh or ay + ah <= by
    if separated:
        print(aid)
        break
    i += 1

# Part 2 - Alternative (check all coordinates, worse performance)

fabric = {}
for d in data:
    id, x, y, w, h = [value for value in d]
    for i in range(x, x + w):
        for j in range(y, y + h):
            if (i, j) not in fabric:
                fabric[(i, j)] = [id]
            else:
                fabric[(i, j)].append(id)
dupes = 0
possibleClaims = {}
for coord in fabric:
    if len(fabric[coord]) == 1 and fabric[coord][0] not in possibleClaims:
        possibleClaims[fabric[coord][0]] = True
    elif len(fabric[coord]) > 1:
        for id in fabric[coord]:
            possibleClaims[id] = False
for id in possibleClaims:
    if possibleClaims[id]:
        print(id)
        break