1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
|
import gleam/io
import gleam/int
import gleam/list
import gleam/dict
import gleam/set.{type Set}
import ext/intx
import ext/listx
import ext/resultx as resx
import ext/genericx as genx
import util/grid
import util/input_util
import util/pos2.{type Pos2}
import util/parser as p
const tile_size = 10
type Tile {
Tile(id: Int, filled: Set(Pos2))
}
fn edge_ids(tile: Tile) -> List(Int) {
let extract = fn(filter, map) {
tile.filled
|> set.to_list
|> list.filter(keeping: filter)
|> list.map(with: fn(pos) { int.bitwise_shift_left(1, map(pos)) })
|> int.sum
}
let dedup = fn(edge_id) {
int.min(
edge_id,
edge_id
|> intx.reverse_bits(tile_size),
)
}
[
extract(fn(b) { pos2.y(b) == 0 }, pos2.x),
extract(fn(b) { pos2.x(b) == 9 }, pos2.y),
extract(fn(b) { pos2.y(b) == 9 }, pos2.x),
extract(fn(b) { pos2.x(b) == 0 }, pos2.y),
]
|> list.map(with: dedup)
}
fn parse_tiles(input: String) -> List(Tile) {
let tile_parser =
p.literal("Tile ")
|> p.proceed(with: p.int())
|> p.skip(p.literal(":\n"))
|> p.then(p.any_str_of_len(tile_size * tile_size + { tile_size - 1 }))
|> p.map2(fn(id, content) {
Tile(
id,
content
|> grid.parse_grid(with: fn(x, y) { #(x, y) }),
)
})
let assert Ok(tiles) =
input
|> p.parse_entire(
with: tile_parser
|> p.sep1(by: p.nlnl())
|> p.skip_ws,
)
tiles
}
fn part1(input: String) -> Int {
let tiles = parse_tiles(input)
let counts =
tiles
|> list.flat_map(with: edge_ids)
|> listx.counts
tiles
|> list.filter(keeping: fn(tile) {
tile
|> edge_ids
|> list.map(with: fn(edge_id) {
counts
|> dict.get(edge_id)
|> resx.assert_unwrap
})
|> listx.count(satisfying: genx.equals(_, 1))
|> genx.equals(2)
})
|> list.map(with: fn(tile) { tile.id })
|> int.product
}
fn part2() -> Nil {
todo
}
pub fn main() -> Nil {
let testing = input_util.read_text("test20")
let assert 20_899_048_083_289 = part1(testing)
let input = input_util.read_text("day20")
io.debug(part1(input))
Nil
}
|
