···

       
6
       
 
       
import gleam/string

     

       
7
       
 
       
import simplifile as file

     

       
8
       
 
       


     

       
9
       
-
       
fn solve(input, size) {

     

       
10
       
-
       
  let get_place = fn(x, y) {

     

       
11
       
-
       
    case

     

       
12
       
-
       
      case x, y {

     

       
13
       
-
       
        _, -1 | -1, _ -> <<>>

     

       
14
       
-
       
        s, _ | _, s if s == size -> <<>>

     

       
15
       
 
       


     

       
16
       
-
       
        _, _ -> bit_array.slice(input, y * size + x, 1) |> result.unwrap(<<>>)

     

       
17
       
-
       
      }

     

       
18
       
-
       
    {

     

       
19
       
-
       
      <<"@">> -> 1

     

       
20
       
-
       
      _ -> 0

     

       
21
       
 
       
    }

     

       
0
       
 
       

     

       
0
       
 
       

     

       
0
       
 
       

     

       
22
       
 
       
  }

     

       
0
       
 
       

     

       
23
       
 
       


     

       
24
       
-
       
  list.range(0, bit_array.byte_size(input) - 1)

     

       
0
       
 
       

     

       
25
       
 
       
  |> list.fold(0, fn(acc, pos) {

     

       
26
       
 
       
    let x = pos % size

     

       
27
       
 
       
    let y = pos / size

     

       
28
       
 
       


     

       
29
       
-
       
    let roll = get_place(x, y)

     

       
30
       
 
       


     

       
31
       
 
       
    let neighbours =

     

       
32
       
-
       
      get_place(x - 1, y - 1)

     

       
33
       
-
       
      + get_place(x, y - 1)

     

       
34
       
-
       
      + get_place(x + 1, y - 1)

     

       
35
       
-
       
      + get_place(x - 1, y)

     

       
36
       
-
       
      + get_place(x + 1, y)

     

       
37
       
-
       
      + get_place(x - 1, y + 1)

     

       
38
       
-
       
      + get_place(x, y + 1)

     

       
39
       
-
       
      + get_place(x + 1, y + 1)

     

       
40
       
 
       


     

       
41
       
 
       
    case roll, neighbours < 4 {

     

       
42
       
 
       
      1, True -> acc + 1

     
···

       
45
       
 
       
  })

     

       
46
       
 
       
}

     

       
47
       
 
       


     

       
0
       
 
       

     

       
0
       
 
       

     

       
0
       
 
       

     

       
0
       
 
       

     

       
0
       
 
       

     

       
0
       
 
       

     

       
0
       
 
       

     

       
0
       
 
       

     

       
0
       
 
       

     

       
0
       
 
       

     

       
0
       
 
       

     

       
0
       
 
       

     

       
0
       
 
       

     

       
0
       
 
       

     

       
0
       
 
       

     

       
0
       
 
       

     

       
0
       
 
       

     

       
0
       
 
       

     

       
0
       
 
       

     

       
0
       
 
       

     

       
0
       
 
       

     

       
0
       
 
       

     

       
0
       
 
       

     

       
0
       
 
       

     

       
0
       
 
       

     

       
0
       
 
       

     

       
0
       
 
       

     

       
0
       
 
       

     

       
0
       
 
       

     

       
0
       
 
       

     

       
0
       
 
       

     

       
0
       
 
       

     

       
0
       
 
       

     

       
48
       
 
       
pub fn main() {

     

       
49
       
 
       
  let assert Ok(input) = file.read(from: "../input.txt")

     

       
50
       
 
       
    as "Input file not found"

     
···

       
54
       
 
       
  let input = input |> list.fold(<<>>, fn(acc, l) { bit_array.append(acc, l) })

     

       
55
       
 
       
  // @ and .

     

       
56
       
 
       


     

       
57
       
-
       
  solve(input, size)

     

       
0
       
 
       

     

       
0
       
 
       

     

       
0
       
 
       

     

       
58
       
 
       
  |> int.to_string

     

       
59
       
 
       
  |> io.println

     

       
60
       
 
       
}

     

···

       
6
       
 
       
import gleam/string

     

       
7
       
 
       
import simplifile as file

     

       
8
       
 
       


     

       
9
       
+
       
fn get_place(x, y, map, size) {

     

       
10
       
+
       
  case

     

       
11
       
+
       
    case x, y {

     

       
12
       
+
       
      _, -1 | -1, _ -> <<>>

     

       
13
       
+
       
      s, _ | _, s if s == size -> <<>>

     

       
0
       
 
       

     

       
14
       
 
       


     

       
15
       
+
       
      _, _ -> bit_array.slice(map, y * size + x, 1) |> result.unwrap(<<>>)

     

       
0
       
 
       

     

       
0
       
 
       

     

       
0
       
 
       

     

       
0
       
 
       

     

       
16
       
 
       
    }

     

       
17
       
+
       
  {

     

       
18
       
+
       
    <<"@">> -> 1

     

       
19
       
+
       
    _ -> 0

     

       
20
       
 
       
  }

     

       
21
       
+
       
}

     

       
22
       
 
       


     

       
23
       
+
       
fn part_1(map, size) {

     

       
24
       
+
       
  list.range(0, bit_array.byte_size(map) - 1)

     

       
25
       
 
       
  |> list.fold(0, fn(acc, pos) {

     

       
26
       
 
       
    let x = pos % size

     

       
27
       
 
       
    let y = pos / size

     

       
28
       
 
       


     

       
29
       
+
       
    let roll = get_place(x, y, map, size)

     

       
30
       
 
       


     

       
31
       
 
       
    let neighbours =

     

       
32
       
+
       
      get_place(x - 1, y - 1, map, size)

     

       
33
       
+
       
      + get_place(x, y - 1, map, size)

     

       
34
       
+
       
      + get_place(x + 1, y - 1, map, size)

     

       
35
       
+
       
      + get_place(x - 1, y, map, size)

     

       
36
       
+
       
      + get_place(x + 1, y, map, size)

     

       
37
       
+
       
      + get_place(x - 1, y + 1, map, size)

     

       
38
       
+
       
      + get_place(x, y + 1, map, size)

     

       
39
       
+
       
      + get_place(x + 1, y + 1, map, size)

     

       
40
       
 
       


     

       
41
       
 
       
    case roll, neighbours < 4 {

     

       
42
       
 
       
      1, True -> acc + 1

     
···

       
45
       
 
       
  })

     

       
46
       
 
       
}

     

       
47
       
 
       


     

       
48
       
+
       
fn part_2(map, size, rolls) {

     

       
49
       
+
       
  let #(rolls, new_map) =

     

       
50
       
+
       
    list.range(0, bit_array.byte_size(map) - 1)

     

       
51
       
+
       
    |> list.fold(#(rolls, <<>>), fn(acc, pos) {

     

       
52
       
+
       
      let #(total, new_map) = acc

     

       
53
       
+
       
      let x = pos % size

     

       
54
       
+
       
      let y = pos / size

     

       
55
       
+
       


     

       
56
       
+
       
      let roll = get_place(x, y, map, size)

     

       
57
       
+
       


     

       
58
       
+
       
      let neighbours =

     

       
59
       
+
       
        get_place(x - 1, y - 1, map, size)

     

       
60
       
+
       
        + get_place(x, y - 1, map, size)

     

       
61
       
+
       
        + get_place(x + 1, y - 1, map, size)

     

       
62
       
+
       
        + get_place(x - 1, y, map, size)

     

       
63
       
+
       
        + get_place(x + 1, y, map, size)

     

       
64
       
+
       
        + get_place(x - 1, y + 1, map, size)

     

       
65
       
+
       
        + get_place(x, y + 1, map, size)

     

       
66
       
+
       
        + get_place(x + 1, y + 1, map, size)

     

       
67
       
+
       


     

       
68
       
+
       
      case roll, neighbours < 4 {

     

       
69
       
+
       
        1, True -> #(total + 1, bit_array.append(new_map, <<".">>))

     

       
70
       
+
       
        0, _ -> #(total, bit_array.append(new_map, <<".">>))

     

       
71
       
+
       
        1, _ | _, _ -> #(total, bit_array.append(new_map, <<"@">>))

     

       
72
       
+
       
      }

     

       
73
       
+
       
    })

     

       
74
       
+
       


     

       
75
       
+
       
  case map == new_map {

     

       
76
       
+
       
    True -> rolls

     

       
77
       
+
       
    False -> part_2(new_map, size, rolls)

     

       
78
       
+
       
  }

     

       
79
       
+
       
}

     

       
80
       
+
       


     

       
81
       
 
       
pub fn main() {

     

       
82
       
 
       
  let assert Ok(input) = file.read(from: "../input.txt")

     

       
83
       
 
       
    as "Input file not found"

     
···

       
87
       
 
       
  let input = input |> list.fold(<<>>, fn(acc, l) { bit_array.append(acc, l) })

     

       
88
       
 
       
  // @ and .

     

       
89
       
 
       


     

       
90
       
+
       
  part_1(input, size)

     

       
91
       
+
       
  |> int.to_string

     

       
92
       
+
       
  |> io.println

     

       
93
       
+
       
  part_2(input, size, 0)

     

       
94
       
 
       
  |> int.to_string

     

       
95
       
 
       
  |> io.println

     

       
96
       
 
       
}