Advent of Code 2022 - Day 18: Boiling Boulders Solution

Part 1

Reject sides that are next to other cubes

Implementation

1const fs = require("fs")
2
3const readData = () => {
4  const data = fs
5    .readFileSync("./input", "utf-8")
6    .split(/\r?\n/)
7    .map(line => [...line.split(",").map(Number)])
8
9  const set = new Set(data.map(String))
10
11  return { data, set }
12}
13
14const main = () => {
15  const { data, set } = readData()
16
17  const dirs = [
18    [-1, 0, 0],
19    [1, 0, 0],
20    [0, -1, 0],
21    [0, 1, 0],
22    [0, 0, -1],
23    [0, 0, 1],
24  ]
25
26  const SIDES_OF_A_CUBE = 6
27
28  const res = data.reduce(
29    (acc, [x, y, z]) =>
30      acc +
31      (SIDES_OF_A_CUBE -
32        dirs
33          .map(([dx, dy, dz]) => String([x + dx, y + dy, z + dz]))
34          .filter(pos => set.has(pos)).length),
35    0
36  )
37
38  console.log(res)
39}
40
41main()

Part 2

Traversal by flooding all cubes (in defined bound (range))

Whenever an adjacent cube is a lava cube, it means we face one side of the lava cube

For better visualization, ignore one dimension

1. . . . .
2. . L . .
3. L x L .
4. * L . .
5. . . . .
6
7at cube *, we face 2 sides of lava cube
8x here is cube of air, which could never be reached

Implementation

1const fs = require("fs")
2
3const readData = () => {
4  const data = fs
5    .readFileSync("./input", "utf-8")
6    .split(/\r?\n/)
7    .map(line => [...line.split(",").map(Number)])
8
9  const set = new Set(data.map(String))
10
11  return { data, set }
12}
13
14const main = () => {
15  const { data: lavaCubes, set: lavaCubesSet } = readData()
16
17  const dirs = [
18    [-1, 0, 0],
19    [1, 0, 0],
20    [0, -1, 0],
21    [0, 1, 0],
22    [0, 0, -1],
23    [0, 0, 1],
24  ]
25
26  const isInRange = (value, range) => range[0] <= value && value <= range[1]
27
28  const [xRange, yRange, zRange] = Array.from({ length: 3 }, (_, i) =>
29    lavaCubes.map(coord => coord[i])
30  ).map(values => [Math.min(...values) - 1, Math.max(...values) + 1])
31
32  let res = 0
33  let queue = [[xRange[0], yRange[0], zRange[0]]]
34  let visited = new Set()
35
36  while (queue.length) {
37    const currentCube = queue.shift()
38
39    if (visited.has(String(currentCube))) continue
40
41    visited.add(String(currentCube))
42
43    const [x, y, z] = currentCube
44
45    const adjacentCubes = dirs
46      .map(([dx, dy, dz]) => [x + dx, y + dy, z + dz])
47      .filter(
48        ([x, y, z]) =>
49          isInRange(x, xRange) && isInRange(y, yRange) && isInRange(z, zRange)
50      )
51
52    for (const adjacentCube of adjacentCubes) {
53      if (lavaCubesSet.has(String(adjacentCube))) {
54        res++
55      } else {
56        queue.push(adjacentCube)
57      }
58    }
59  }
60
61  console.log(res)
62}
63
64main()

References

Original problem

Flood fill (Wikipedia)