aoc2022/d18/part2.py

import sys

S = set()  # cubes
for l in sys.stdin.read().splitlines():
    (x,y,z) = list(map(int,l.split(',')))  # makes type of tuple explicite for codon
    S.add((x,y,z))

A = 23
L = set()  # water
for x in range(-2,A+1):
    for y in range(-2,A+1):
        L.add((x,y,-2))

more = True
while more:
    more = False
    for x in range(-2,A+1):
        for y in range(-2,A+1):
            for z in range(-2,A+1):
                if (x,y,z) not in S and (x,y,z) not in L: # water can only expand in air
                    for (i,j,k) in [(0,0,1),(0,0,-1),(0,1,0),(0,-1,0),(1,0,0),(-1,0,0)]:
                        if (x+i,y+j,z+k) in L: # if neighbour is water
                            L.add((x,y,z)) # water expand
                            more = True
                            break

N = 0
for (x,y,z) in S:
    for (i,j,k) in [(0,0,1),(0,0,-1),(0,1,0),(0,-1,0),(1,0,0),(-1,0,0)]:
        if (x+i,y+j,z+k) in L:
            N += 1
print(N)

# ~/.local/programs/codon/bin/codon build --relocation-model=static --release -o part2 part2.py