problem22.py

import numpy as np
import re
fh = open("input22")

cubes = []
X, Y, Z = set(), set(), set()
for i, line in enumerate(fh):
    line = line.strip()
    m = re.match("(on|off) x=([^.]*)..([^,]*),y=([^.]*)..([^,]*),z=([^.]*)..(.*)", line)
    action, *coords = m.groups()
    arr = np.array([int(c) for c in coords])
    arr += np.array([0, 1, 0, 1, 0, 1])
    g = iter(arr)
    x, y, z = zip(g, g)
    X |= set(x)
    Y |= set(y)
    Z |= set(z)
    cubes.append((x, y, z, action == "on"))

X = sorted(X)
Y = sorted(Y)
Z = sorted(Z)
volumes = np.einsum("i,j,k", np.diff(X), np.diff(Y), np.diff(Z))
Xdict = {x: i for i, x in enumerate(X)}
Ydict = {y: i for i, y in enumerate(Y)}
Zdict = {z: i for i, z in enumerate(Z)}
area = np.zeros((len(X) - 1, len(Y) - 1, len(Z) - 1), "bool")
for x, y, z, action in cubes:
    area[Xdict[x[0]]:Xdict[x[1]], Ydict[y[0]]:Ydict[y[1]], Zdict[z[0]]:Zdict[z[1]]] = action
print(np.sum(volumes[area]))