Day 4: Giant Squid
Part 1
[drawn_nums_raw | raw_boards] =
"""
7,4,9,5,11,17,23,2,0,14,21,24,10,16,13,6,15,25,12,22,18,20,8,19,3,26,1
22 13 17 11 0
8 2 23 4 24
21 9 14 16 7
6 10 3 18 5
1 12 20 15 19
3 15 0 2 22
9 18 13 17 5
19 8 7 25 23
20 11 10 24 4
14 21 16 12 6
14 21 17 24 4
10 16 15 9 19
18 8 23 26 20
22 11 13 6 5
2 0 12 3 7
"""
|> String.split("\n\n")
boards =
raw_boards
|> Enum.map(fn e ->
String.split(e, ["\n", " "], trim: true)
|> Enum.map(&String.to_integer/1)
|> Enum.chunk_every(5)
end)
drawn_nums = drawn_nums_raw |> String.split(",") |> Enum.map(&String.to_integer/1)
[7, 4, 9, 5, 11, 17, 23, 2, 0, 14, 21, 24, 10, 16, 13, 6, 15, 25, 12, 22, 18, 20, 8, 19, 3, 26, 1]
defmodule Part1 do
def transpose(board), do: board |> List.zip() |> Enum.map(&Tuple.to_list/1)
def draw_num_and_mark(boards, drawn_number) do
boards
|> Enum.map(fn board ->
board |> Enum.map(fn row -> Enum.map(row, &if(&1 == drawn_number, do: "x", else: &1)) end)
end)
end
def winning?(board) do
winning_row = board |> Enum.any?(fn row -> Enum.all?(row, &(&1 == "x")) end)
winning_col = transpose(board) |> Enum.any?(fn row -> Enum.all?(row, &(&1 == "x")) end)
winning_row || winning_col
end
def find_first_winning_board(_, [], _, _), do: raise("No winning boards")
def find_first_winning_board(boards, [drawn_number | other_nums], nil, _) do
new_boards = draw_num_and_mark(boards, drawn_number)
find_first_winning_board(
new_boards,
other_nums,
Enum.find(new_boards, &winning?/1),
drawn_number
)
end
def find_first_winning_board(_, _, winning_board, last_drawn), do: {winning_board, last_drawn}
def find_last_winning_board(_, [], _, _), do: raise("No winning boards")
def find_last_winning_board([board | []], nums, _),
do: find_first_winning_board([board], nums, nil, nil)
def find_last_winning_board(boards, [drawn_number | other_nums], _) do
draw_num_and_mark(boards, drawn_number)
|> Enum.filter(fn board -> !winning?(board) end)
|> find_last_winning_board(other_nums, drawn_number)
end
end
{winning_board, last_drawn} = Part1.find_first_winning_board(boards, drawn_nums, nil, nil)
board_sum =
winning_board
|> Enum.reduce(0, fn r, a ->
a + (r |> Enum.filter(&(&1 != "x")) |> Enum.sum())
end)
IO.inspect(board_sum * last_drawn, label: "Part 1 result")
Part 1 result: 4512
4512
[drawn_nums_raw | raw_boards] =
"""
93,35,66,15,6,51,49,67,16,77,80,8,1,57,99,92,14,9,13,23,33,11,43,50,60,96,40,25,22,39,56,18,2,7,34,68,26,90,75,41,4,95,71,30,42,5,46,55,27,98,79,12,65,73,29,28,17,48,81,32,59,63,85,91,52,21,38,31,61,83,97,62,44,70,19,69,36,47,74,58,78,24,72,0,10,88,37,87,3,45,82,76,54,84,20,94,86,53,64,89
14 33 79 61 44
85 60 38 13 48
51 34 11 19 7
21 30 73 6 76
41 4 65 18 91
3 82 68 26 93
61 90 29 69 92
60 94 99 6 83
77 80 2 58 55
59 65 95 38 62
41 9 73 71 74
66 24 45 5 55
97 82 53 63 16
12 19 88 87 27
31 8 75 98 83
63 24 86 90 45
41 92 42 83 77
64 28 54 94 10
15 93 57 29 50
23 39 37 48 38
1 31 7 0 54
9 59 79 19 96
51 14 77 38 45
30 76 42 65 91
72 60 37 43 71
22 81 40 97 27
83 28 41 1 76
69 68 64 57 78
59 38 63 89 29
8 58 18 66 72
39 32 21 94 37
20 1 66 82 52
10 56 40 13 62
59 96 44 75 50
41 83 6 90 28
90 33 1 57 34
14 86 93 92 68
54 37 95 11 77
88 13 62 72 48
96 65 67 85 80
47 48 82 96 85
78 91 42 38 11
79 94 49 24 27
56 92 72 45 73
75 0 70 4 68
48 51 94 17 58
37 88 56 66 16
27 97 14 45 83
53 39 6 5 68
47 57 28 31 11
35 66 19 68 73
41 49 10 80 48
39 50 79 23 59
15 45 40 17 75
88 86 71 8 0
58 48 41 22 11
97 59 17 71 44
6 24 49 84 42
89 27 23 82 9
60 86 90 65 34
11 58 2 98 26
90 52 60 14 12
69 63 56 36 30
3 44 19 5 85
95 84 31 51 79
39 62 64 29 24
56 9 0 18 3
22 74 77 47 98
55 93 79 4 33
78 53 11 26 75
38 82 8 25 55
74 1 21 30 46
12 4 62 45 52
24 39 0 92 15
19 54 51 57 88
16 28 48 19 43
58 96 67 22 61
8 9 74 5 81
78 59 49 71 15
82 46 42 32 70
73 89 80 92 42
4 60 99 75 39
5 50 64 98 91
49 11 9 51 85
27 97 54 93 14
70 41 37 53 62
0 57 48 39 61
10 85 59 74 76
2 7 1 4 81
26 78 60 80 72
8 50 43 73 80
74 86 64 95 30
45 69 71 65 55
52 66 36 62 60
25 53 63 46 5
5 57 15 82 46
23 96 72 29 43
98 91 42 51 99
70 25 64 45 16
4 40 48 97 11
37 93 48 23 99
98 8 21 78 36
52 73 5 55 11
63 42 88 38 94
1 80 71 68 15
51 34 66 87 17
20 54 74 14 55
84 64 96 31 2
62 43 76 5 45
98 71 50 56 82
13 59 67 25 94
41 89 27 60 2
77 31 48 63 62
24 49 32 76 87
70 85 51 52 66
31 22 23 36 47
45 55 61 89 72
62 81 35 79 8
24 82 38 91 76
74 5 29 94 58
2 41 6 13 34
86 46 44 38 56
28 19 50 1 12
96 23 33 91 64
7 89 59 9 70
81 69 97 10 87
83 56 7 53 96
93 42 68 29 62
78 66 2 55 60
4 5 15 98 99
80 40 93 94 25
95 99 55 31 12
29 90 43 52 38
51 64 92 37 77
21 4 85 20 17
44 73 69 38 95
11 47 19 83 91
96 92 22 31 21
70 62 88 25 82
18 40 98 34 94
6 14 86 29 99
8 5 15 38 90
44 43 51 77 80
78 32 75 83 3
53 13 71 66 52
55 3 93 75 54
58 57 60 15 70
67 51 81 96 74
6 35 29 32 44
38 56 5 50 88
38 46 11 16 33
83 6 88 93 43
42 56 77 9 85
76 69 49 58 22
15 14 4 54 23
27 84 97 50 46
98 14 60 87 72
20 38 74 13 32
18 96 92 21 99
93 43 86 16 66
53 12 29 78 41
13 70 71 4 97
44 1 37 84 49
17 0 22 72 63
61 66 60 32 68
92 44 20 56 69
73 22 18 31 48
71 93 83 16 49
81 89 79 38 30
80 24 26 86 62
82 58 76 20 5
56 34 84 80 38
12 49 8 52 91
41 62 1 77 48
23 83 51 81 2
77 5 96 13 52
61 85 46 54 48
56 80 20 83 69
39 42 28 87 16
59 40 45 58 62
35 87 52 85 9
18 55 71 63 58
86 28 20 5 68
26 76 93 66 44
53 2 95 6 60
19 53 33 59 27
58 95 74 26 9
98 25 49 92 44
76 20 41 66 88
47 50 57 24 28
54 63 31 74 72
91 19 3 23 14
85 44 66 55 33
18 17 86 7 78
42 22 15 99 93
33 31 15 40 44
41 86 18 94 66
19 69 91 76 95
99 11 70 42 56
68 82 90 12 83
79 21 74 63 22
99 76 27 17 34
91 52 14 2 26
13 93 81 35 75
48 62 0 39 6
61 3 96 95 10
4 39 22 29 49
5 7 15 54 83
2 33 65 62 14
8 73 24 47 87
24 75 54 90 5
59 26 52 37 23
11 36 42 47 93
44 88 45 21 96
6 58 73 60 86
57 2 67 75 90
87 51 80 35 24
98 36 79 5 21
6 78 0 94 25
16 3 81 41 45
63 84 58 52 9
38 57 87 20 40
5 68 14 98 29
71 88 21 80 61
3 43 31 48 26
2 92 45 28 18
89 20 90 42 99
40 52 87 63 91
13 31 59 24 29
70 79 34 82 15
95 82 62 2 53
63 19 10 42 16
69 28 22 92 56
11 3 17 76 71
58 70 27 6 93
83 43 99 11 58
9 79 4 76 6
18 49 56 36 72
31 91 8 34 78
7 96 66 98 95
87 31 90 33 53
70 39 50 73 3
89 17 64 97 65
11 85 42 57 6
88 44 26 47 54
37 90 50 65 25
68 15 87 33 0
24 63 30 98 57
13 7 93 22 34
55 75 70 14 16
48 77 51 15 33
84 52 22 73 67
25 47 34 95 89
3 45 42 17 93
56 53 68 72 8
60 44 46 84 70
34 94 76 79 98
36 37 59 90 22
23 39 2 48 15
81 4 7 3 21
60 58 26 10 66
53 18 38 80 24
93 56 11 27 21
51 86 94 64 52
65 57 28 98 69
32 45 64 94 68
66 67 53 50 16
37 60 10 33 70
76 87 69 78 88
71 99 63 38 25
54 14 31 45 40
27 17 91 78 96
70 84 11 98 75
6 94 72 88 18
65 9 56 33 92
40 33 82 38 85
98 91 44 26 57
73 34 32 25 46
58 8 16 42 95
20 1 67 54 90
34 88 27 63 73
92 70 5 21 15
1 82 74 9 23
33 66 78 85 30
3 75 53 37 72
22 11 43 8 69
57 30 72 26 58
45 55 23 88 21
53 0 19 31 65
62 66 46 39 15
57 71 75 51 44
49 96 10 53 47
77 93 28 91 74
70 41 79 89 97
26 45 59 56 80
28 69 48 13 43
10 75 80 58 40
1 92 82 94 33
47 74 60 53 18
51 11 77 9 55
50 3 89 47 34
26 15 68 79 45
94 90 19 59 73
62 29 46 74 44
91 5 39 10 14
11 49 87 19 2
9 33 71 57 66
82 46 83 64 55
52 76 67 15 73
88 39 34 85 61
34 82 64 97 39
53 30 71 22 85
73 86 88 93 44
56 25 52 87 4
67 7 31 2 83
9 6 54 84 46
4 75 65 63 1
81 66 72 71 43
17 61 51 48 35
14 56 70 50 13
0 48 33 27 35
7 20 9 97 46
8 13 52 11 24
40 56 50 64 75
32 92 36 54 5
19 49 78 92 20
97 87 80 64 9
26 34 67 21 91
63 85 68 88 28
18 93 41 31 79
97 13 9 26 58
1 19 76 31 51
95 65 37 48 88
92 72 98 10 43
69 28 29 5 62
81 86 83 31 43
37 95 51 42 17
54 3 99 23 40
15 72 16 4 78
49 48 76 38 52
66 97 55 6 62
38 95 58 7 96
61 93 45 41 50
13 51 92 2 52
15 8 36 37 17
27 60 58 69 16
0 92 24 25 61
65 28 52 20 99
87 12 3 21 31
48 67 63 70 11
51 32 36 37 62
33 38 46 6 63
88 97 67 72 84
54 23 3 81 94
59 50 40 11 21
30 22 59 53 35
46 88 12 9 78
95 31 39 10 67
86 73 42 43 1
93 21 16 51 28
61 98 77 62 41
42 93 58 66 89
64 14 18 67 76
21 17 43 79 44
47 0 20 95 97
47 75 70 8 26
82 98 13 61 96
94 74 17 78 30
15 85 46 31 11
99 28 39 51 92
8 54 19 9 30
63 90 99 7 50
14 45 74 65 82
10 76 85 21 20
80 48 94 6 93
32 13 76 35 2
57 51 25 43 85
89 87 26 15 95
24 67 33 34 14
23 47 39 64 71
83 82 79 50 23
77 60 67 8 32
55 38 33 26 37
17 36 69 44 43
49 9 52 70 39
94 79 82 74 99
7 90 6 76 3
0 91 81 11 17
2 28 29 22 78
33 1 23 16 86
53 18 72 38 1
75 70 19 10 99
34 60 30 61 95
80 78 51 83 22
25 23 11 6 44
8 17 15 21 6
46 79 77 11 23
25 14 59 42 95
50 16 90 49 2
81 56 51 96 76
37 27 62 8 35
67 81 84 47 53
32 13 80 15 66
95 94 59 38 97
64 26 63 75 78
23 71 88 61 20
35 32 59 10 67
17 36 38 89 75
74 8 30 57 39
97 58 55 70 15
82 37 71 56 15
92 66 10 1 14
26 60 70 50 89
97 58 83 3 61
41 6 35 88 13
16 7 54 9 31
47 91 50 17 51
6 38 24 14 69
48 3 0 77 5
43 86 70 80 40
39 94 95 47 98
46 41 45 38 48
18 73 56 99 76
74 75 26 30 16
42 11 85 86 51
39 68 42 79 14
48 90 75 4 41
34 76 63 49 83
64 86 92 98 65
40 15 54 20 1
17 4 47 37 8
19 15 36 6 60
23 5 24 87 55
51 12 94 18 90
81 3 86 39 88
58 46 25 13 81
72 17 64 28 51
91 1 55 57 49
20 39 11 5 52
60 22 24 15 53
40 50 55 39 6
79 38 44 52 81
83 36 11 42 88
48 4 32 8 71
34 65 51 2 46
21 47 96 94 19
31 38 55 64 24
36 57 32 9 34
43 61 11 41 56
58 2 4 28 59
47 14 83 62 76
18 61 22 80 54
24 87 49 13 40
44 82 34 78 10
94 55 29 95 71
68 54 76 1 39
46 4 50 82 85
75 26 43 58 98
29 47 49 81 12
14 19 57 11 41
65 38 2 0 57
23 19 4 79 70
88 8 73 25 34
15 28 77 24 39
31 97 11 62 37
29 26 19 14 40
12 88 22 42 96
95 63 78 21 53
35 50 9 39 43
10 46 24 87 13
4 94 52 42 67
71 33 15 75 80
45 49 61 64 58
35 37 62 55 30
87 79 31 96 41
75 61 94 3 52
59 13 35 53 54
85 81 79 96 57
36 38 40 28 93
70 95 39 43 5
33 79 74 21 32
0 18 43 5 28
82 63 66 56 27
42 76 61 98 73
83 9 2 96 23
96 47 61 45 89
40 77 15 55 25
23 39 10 18 91
31 70 1 30 75
67 94 37 4 51
3 5 10 80 89
60 17 42 55 92
38 32 52 0 56
96 61 79 34 90
43 2 98 4 27
74 95 14 35 49
67 66 57 76 88
89 71 68 69 48
20 70 3 0 12
13 21 15 51 24
"""
|> String.split("\n\n")
boards =
raw_boards
|> Enum.map(fn e ->
String.split(e, ["\n", " "], trim: true)
|> Enum.map(&String.to_integer/1)
|> Enum.chunk_every(5)
end)
drawn_nums = drawn_nums_raw |> String.split(",") |> Enum.map(&String.to_integer/1)
[93, 35, 66, 15, 6, 51, 49, 67, 16, 77, 80, 8, 1, 57, 99, 92, 14, 9, 13, 23, 33, 11, 43, 50, 60, 96,
40, 25, 22, 39, 56, 18, 2, 7, 34, 68, 26, 90, 75, 41, 4, 95, 71, 30, 42, 5, 46, 55, 27, 98, ...]
{winning_board, last_drawn} = Part1.find_first_winning_board(boards, drawn_nums, nil, nil)
board_sum =
winning_board
|> Enum.reduce(0, fn r, a ->
a + (r |> Enum.filter(&(&1 != "x")) |> Enum.sum())
end)
IO.inspect(board_sum * last_drawn, label: "Part 1 result")
Part 1 result: 27027
27027
Part 2
{last_winning_board, last_drawn_last_board} =
Part1.find_last_winning_board(boards, drawn_nums, nil)
|> IO.inspect(label: "last winning board, and drawn number")
last_board_sum =
last_winning_board
|> Enum.reduce(0, fn r, a ->
a + (r |> Enum.filter(&(&1 != "x")) |> Enum.sum())
end)
IO.inspect(last_board_sum * last_drawn_last_board, label: "Part 2 result")
last winning board, and drawn number: {[
["x", "x", "x", "x", "x"],
[20, 54, "x", "x", "x"],
[84, 64, "x", "x", "x"],
["x", "x", 76, "x", 45],
["x", "x", "x", "x", 82]
], 87}
Part 2 result: 36975
36975
