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
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
|
use advent_lib::prelude::*;
use std::collections::HashMap;
use std::collections::HashSet;
#[derive(PartialEq, Eq, Hash, Debug, Clone)]
enum Cave {
Start,
End,
Small(String),
Large(String),
}
fn main() -> Result<()> {
let mut args = std::env::args();
if args.len() != 2 {
eprintln!("Usage: advent input");
}
let _ = args.next();
let filename = args.next().unwrap();
let input = advent_lib::read_lines_file(&filename)?;
let mut connections: HashMap<Cave,Vec<Cave>> = HashMap::new();
for line in &input {
let words: Vec<&str> = line.split('-').collect();
let a = parse_cave(words[0]);
let b = parse_cave(words[1]);
match connections.get_mut(&a) {
None => {
let mut destinations = Vec::new();
destinations.push(b.clone());
connections.insert(a.clone(), destinations);
}
Some(destinations) => {
destinations.push(b.clone());
}
}
match connections.get_mut(&b) {
None => {
let mut destinations = Vec::new();
destinations.push(a.clone());
connections.insert(b.clone(), destinations);
}
Some(destinations) => {
destinations.push(a.clone());
}
}
}
let path_count = tour_caves(Cave::Start, &connections, HashSet::new());
println!("{}", path_count);
let longer_path_count = longer_tour_caves(Cave::Start, &connections,
HashMap::new(), false);
println!("{}", longer_path_count);
Ok(())
}
fn parse_cave(name: &str) -> Cave {
if name == "start" {
Cave::Start
} else if name == "end" {
Cave::End
} else if name.chars().nth(0).unwrap().is_uppercase() {
Cave::Large(name.to_string())
} else {
Cave::Small(name.to_string())
}
}
fn tour_caves(here: Cave, map: &HashMap<Cave,Vec<Cave>>,
visited: HashSet<Cave>)
-> i64
{
if here == Cave::End {
return 1;
}
let mut path_count = 0;
for destination in map.get(&here).unwrap() {
if !visited.contains(destination) {
let mut new_visited = visited.clone();
match here {
Cave::Large(_) => { },
_ => {
new_visited.insert(here.clone());
}
}
path_count += tour_caves(destination.clone(), map, new_visited);
}
}
path_count
}
fn longer_tour_caves(here: Cave, map: &HashMap<Cave,Vec<Cave>>,
visited: HashMap<Cave,usize>, have_double_visited: bool)
-> i64
{
if here == Cave::End {
return 1;
}
let mut path_count = 0;
for destination in map.get(&here).unwrap() {
let (should_go, new_have_double_visited) = match visited.get(destination)
{
None => (true, have_double_visited),
Some(1) => {
if have_double_visited {
(false, true)
} else {
(true, true)
}
}
_ => (false, have_double_visited),
};
if should_go {
let mut new_visited = visited.clone();
let here_visit_count = visited.get(&here);
match here {
Cave::Large(_) => { },
Cave::Small(_) => {
new_visited.insert(here.clone(), match here_visit_count {
None => 1,
Some(n) => n + 1,
});
}
Cave::Start => {
new_visited.insert(here.clone(), 2);
}
Cave::End => {
new_visited.insert(here.clone(), 2);
}
}
path_count += longer_tour_caves(destination.clone(), map, new_visited,
new_have_double_visited);
}
}
path_count
}
|