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
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
|
import gleam/io
import gleam/int
import gleam/list
import gleam/bool
import gleam/string as str
import gleam/function as fun
import gleam/set.{type Set}
import gleam/order.{Eq, Gt, Lt}
import gleam/option.{type Option, None, Some}
import ext/boolx
import ext/resultx as resx
import util/input_util
type Player {
P1
P2
}
type Game {
Game(p1: List(Int), p2: List(Int))
}
fn parse_game(input: String) -> Game {
let assert [p1, p2] =
input
|> str.trim()
|> str.split("\n\n")
|> list.map(with: fn(part) {
part
|> str.split("\n")
|> list.rest
|> resx.assert_unwrap
|> list.map(with: fun.compose(int.parse, resx.assert_unwrap))
})
Game(p1, p2)
}
fn score(deck: List(Int)) -> Int {
deck
|> list.reverse
|> list.index_fold(from: 0, with: fn(sum, card, index) {
sum + card * { index + 1 }
})
}
fn outcome(game: Game) -> Option(Int) {
use <- bool.guard(when: game.p2 == [], return: Some(score(game.p1)))
use <- bool.guard(when: game.p1 == [], return: Some(-score(game.p2)))
None
}
fn get_winner(score: Int) -> Player {
case int.compare(score, 0) {
Lt -> P2
Eq -> panic
Gt -> P1
}
}
fn play_combat_game(game: Game) -> Int {
use <- option.lazy_unwrap(outcome(game))
let assert Game([top1, ..rest1], [top2, ..rest2]) = game
play_combat_game(case int.compare(top1, top2) {
Lt -> Game(rest1, list.append(rest2, [top2, top1]))
Eq -> panic
Gt -> Game(list.append(rest1, [top1, top2]), rest2)
})
}
fn part1(input: String) -> Int {
input
|> parse_game
|> play_combat_game
|> int.absolute_value
}
fn play_recursive_combat(game: Game, seen: Set(Game)) -> Int {
use <- option.lazy_unwrap(outcome(game))
use <- bool.guard(when: set.contains(seen, game), return: score(game.p1))
let assert Game([top1, ..rest1], [top2, ..rest2]) = game
let seen = set.insert(seen, game)
let winner = {
use <- boolx.guard_lazy(
when: list.length(rest1) >= top1
&& list.length(rest2) >= top2,
return: fn() {
Game(list.take(rest1, top1), list.take(rest2, top2))
|> play_recursive_combat(set.new())
|> get_winner
},
)
case int.compare(top1, top2) {
Lt -> P2
Eq -> panic
Gt -> P1
}
}
play_recursive_combat(
case winner {
P1 -> Game(list.append(rest1, [top1, top2]), rest2)
P2 -> Game(rest1, list.append(rest2, [top2, top1]))
},
seen,
)
}
fn part2(input: String) -> Int {
input
|> parse_game
|> play_recursive_combat(set.new())
|> int.absolute_value
}
pub fn main() -> Nil {
let testing = input_util.read_text("test22")
let assert 306 = part1(testing)
let assert 291 = part2(testing)
let input = input_util.read_text("day22")
io.debug(part1(input))
io.debug(part2(input))
Nil
}
|
