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
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
|
#![allow(dead_code)]
#![allow(unused_variables)]
use crate::prelude::*;
enum Node {
Dir(HashMap<String, Node>),
File(i64),
}
impl Node {
fn new_dir() -> Self {
Self::Dir(HashMap::new())
}
fn new_file(size: i64) -> Self {
Self::File(size)
}
fn size(&self) -> i64 {
match self {
Self::File(size) => *size,
Self::Dir(children) => children
.values()
.map(|child| child.size())
.sum(),
}
}
fn iter(&self) -> NodeIter<'_> {
let mut next = std::collections::VecDeque::new();
next.push_back(("", self));
NodeIter { next }
}
fn resolve_path(&mut self, path: &[String]) -> &mut Self {
let mut pwd = self;
for name in path {
let Node::Dir(children) = pwd
else { panic!("invalid path") };
pwd = children.get_mut(name).unwrap();
}
pwd
}
}
struct NodeIter<'a> {
next: std::collections::VecDeque<(&'a str, &'a Node)>,
}
impl<'a> Iterator for NodeIter<'a> {
type Item = (&'a str, &'a Node);
fn next(&mut self) -> Option<Self::Item> {
let Some(next) = self.next.pop_back()
else { return None };
if let Node::Dir(children) = next.1 {
for (name, child) in children.iter() {
self.next.push_front((name, child));
}
}
Some(next)
}
}
pub struct DirTree {
root: Node,
}
pub fn parse(fh: File) -> Result<DirTree> {
let mut lines = parse::lines(fh).peekable();
let mut root = Node::new_dir();
let mut path = vec![];
while let Some(cmdline) = lines.by_ref().next() {
let Some(captures) = ®ex_captures!(
r"^\$ (cd|ls)(?: (.*))?$",
&cmdline
)
else { bail!("didn't match cmdline: '{}'", cmdline) };
let Some(cmd) = captures.get(1)
else { bail!("no cmd found in cmdline: '{}'", cmdline) };
let pwd = root.resolve_path(&path);
match cmd.as_str() {
"cd" => {
let Some(arg) = captures.get(2)
else { bail!("no arg found for cd: '{}'", cmdline) };
match arg.as_str() {
".." => {
path.pop();
}
"/" => path = vec![],
dirname => {
let Node::Dir(children) = pwd
else { panic!("invalid path") };
if !children.contains_key(dirname) {
children.insert(
dirname.to_string(),
Node::new_dir(),
);
}
path.push(dirname.to_string());
}
}
}
"ls" => {
loop {
let Node::Dir(children) = pwd
else { panic!("invalid path") };
let Some(lsline) = lines.peek()
else { break };
let Some(captures) = ®ex_captures!(
r"^(dir|[0-9]+) (.*)$",
lsline
)
else { break };
let Some(data) = captures.get(1)
else { break };
let Some(name) = captures.get(2)
else { break };
let node = match data.as_str() {
"dir" => Node::new_dir(),
size => Node::new_file(size.parse().unwrap()),
};
children.insert(name.as_str().to_string(), node);
lines.next();
}
}
_ => unreachable!(),
}
}
Ok(DirTree { root })
}
pub fn part1(tree: DirTree) -> Result<i64> {
let mut total = 0;
for (name, node) in tree.root.iter() {
if matches!(node, Node::File(_)) {
continue;
}
let size = node.size();
if size <= 100_000 {
total += size;
}
}
Ok(total)
}
pub fn part2(tree: DirTree) -> Result<i64> {
let total = tree.root.size();
let free = 70_000_000 - total;
let needed = 30_000_000 - free;
let mut possible = vec![];
for (name, node) in tree.root.iter() {
if matches!(node, Node::File(_)) {
continue;
}
let size = node.size();
if size > needed {
possible.push(size);
}
}
Ok(possible.iter().copied().min().unwrap())
}
#[test]
fn test() {
assert_eq!(
part1(parse(parse::data(2022, 7).unwrap()).unwrap()).unwrap(),
1297683
);
assert_eq!(
part2(parse(parse::data(2022, 7).unwrap()).unwrap()).unwrap(),
5756764
);
}
|
