114 lines
2.9 KiB
Python
114 lines
2.9 KiB
Python
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#!/bin/python3
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from collections import defaultdict
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from queue import Queue
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cubes = set()
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with open('inputs/day18.txt', 'r') as f:
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for line in f:
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[x, y, z] = line.split(',')
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cubes.add((int(x), int(y), int(z)))
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def ordered(pos1, pos2):
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if pos1 > pos2:
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return (pos1, pos2)
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else:
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return (pos2, pos1)
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sides = defaultdict(lambda: 0)
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for cube in cubes:
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(x, y, z) = cube
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cube_sides = []
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cube_sides.append(ordered(cube, (x+1, y, z)))
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cube_sides.append(ordered(cube, (x-1, y, z)))
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cube_sides.append(ordered(cube, (x, y+1, z)))
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cube_sides.append(ordered(cube, (x, y-1, z)))
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cube_sides.append(ordered(cube, (x, y, z+1)))
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cube_sides.append(ordered(cube, (x, y, z-1)))
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for side in cube_sides:
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sides[side] += 1
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outer_sides = set()
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for side, count in sides.items():
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if count == 1:
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outer_sides.add(side)
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print("part1", len(outer_sides))
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# Determine max and min coords
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x_min = min(map(lambda a: a[0], cubes))
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x_max = max(map(lambda a: a[0], cubes))
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y_min = min(map(lambda a: a[1], cubes))
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y_max = max(map(lambda a: a[1], cubes))
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z_min = min(map(lambda a: a[2], cubes))
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z_max = max(map(lambda a: a[2], cubes))
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# Increase bounds by 1 in all directions
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x_min -= 1
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x_max += 1
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y_min -= 1
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y_max += 1
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z_min -= 1
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z_max += 1
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# Flood fill from 1 corner to find all reachable cubes.
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class SetQueue(Queue):
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def _init(self, maxsize):
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self.queue = set()
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def _put(self, item):
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self.queue.add(item)
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def _get(self):
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return self.queue.pop()
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cube_queue = SetQueue()
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cube_queue.put((x_min, y_min, z_min))
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reachable_cubes = set()
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max_cubes = (x_max - x_min) * (y_max - y_min) * (z_max - z_min)
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while True:
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if cube_queue.empty():
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break
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cube = cube_queue.get()
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(x, y, z) = cube
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reachable_cubes.add(cube)
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neighbors = []
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neighbors.append((x+1, y, z))
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neighbors.append((x-1, y, z))
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neighbors.append((x, y+1, z))
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neighbors.append((x, y-1, z))
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neighbors.append((x, y, z+1))
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neighbors.append((x, y, z-1))
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for neighbor in neighbors:
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(nx, ny, nz) = neighbor
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if nx < x_min or nx > x_max or ny < y_min or ny > y_max or nz < z_min or nz > z_max:
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continue
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if neighbor in reachable_cubes or neighbor in cubes:
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continue
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# Found a new empty cube!
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cube_queue.put(neighbor)
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# Okay, found all empty cube outside the droplet.
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surface_sides = set()
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for empty in reachable_cubes:
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(x, y, z) = empty
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cube_sides = []
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cube_sides.append(ordered(empty, (x+1, y, z)))
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cube_sides.append(ordered(empty, (x-1, y, z)))
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cube_sides.append(ordered(empty, (x, y+1, z)))
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cube_sides.append(ordered(empty, (x, y-1, z)))
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cube_sides.append(ordered(empty, (x, y, z+1)))
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cube_sides.append(ordered(empty, (x, y, z-1)))
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for side in cube_sides:
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if side in outer_sides:
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surface_sides.add(side)
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print("part2", len(surface_sides))
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