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
|
use std::io::BufReader;
use std::io::prelude::*;
use std::fs::File;
#[derive(Debug, Clone, Copy)]
struct Marker {
take: usize,
repeat: usize
}
#[derive(Debug, Clone, Copy)]
enum Token {
Marker(usize, Marker),
Literal(usize)
}
impl Token {
fn size(self) -> usize {
match self {
Token::Marker(x, _) => x,
Token::Literal(x) => x
}
}
fn is_marker(self) -> bool {
match self {
Token::Marker(_, _) => true,
Token::Literal(_) => false
}
}
fn unwrap_marker(self) -> Marker {
match self {
Token::Marker(_, marker) => marker,
Token::Literal(_) => panic!("Bad unwrap marker")
}
}
}
fn main() {
let mut tokens = parse(read_file());
tokens.reverse();
let mut length: u64 = 0;
while tokens.len() > 0 {
let next = tokens.pop().unwrap();
if next.is_marker() {
let marker = next.unwrap_marker();
let mut used_take = 0;
let mut tokens_to_repeat = Vec::new();
while used_take < marker.take {
let next_token = tokens.pop().unwrap();
if used_take + next_token.size() <= marker.take {
tokens_to_repeat.push(next_token);
}
else {
assert!(!next_token.is_marker());
//assume splits only happen on literals
tokens_to_repeat.push(Token::Literal(marker.take - used_take));
tokens.push(Token::Literal(next_token.size() - marker.take + used_take));
}
used_take += next_token.size();
}
tokens_to_repeat.reverse();
for _ in 0..marker.repeat {
for &token in &tokens_to_repeat {
tokens.push(token);
}
}
} else {
length += next.size() as u64;
}
}
println!("Length: {}", length);
}
fn parse(text: String) -> Vec<Token> {
let mut tokens = Vec::new();
let mut chars = text.chars();
let mut current_char = chars.next();
while current_char.is_some() {
let c = current_char.unwrap();
if c == '(' {
let mut char_count = 1;
let mut take_str = String::new();
let mut repeat_str = String::new();
loop {
let n = chars.next().unwrap();
char_count += 1;
if n == 'x' { break; }
take_str.push(n);
}
loop {
let n = chars.next().unwrap();
char_count += 1;
if n == ')' { break; }
repeat_str.push(n);
}
let take: usize = take_str.parse().expect(format!("Tried to parse take {}", take_str).as_ref());
let repeat: usize = repeat_str.parse().expect(format!("Tried to parse repeat {}", repeat_str).as_ref());
tokens.push(Token::Marker(char_count , Marker{take: take, repeat:repeat}));
} else {
assert!(c != '(' && c != ')');
tokens.push(Token::Literal(1));
}
current_char = chars.next();
}
collapse_literals(&mut tokens);
tokens
}
fn collapse_literals(tokens: &mut Vec<Token>) {
let mut i = 0;
while i < tokens.len()-1 {
match (tokens[i], tokens[i+1]) {
(Token::Literal(l1), Token::Literal(l2)) => {
tokens[i] = Token::Literal(l1+l2);
tokens.remove(i+1);
},
_ => {
i += 1;
}
}
}
}
fn read_file() -> String {
let file = BufReader::new(File::open("input.txt").unwrap());
file.lines()
.map(|line| line.unwrap().trim().to_string())
.filter(|line| line.len() > 0)
.next()
.unwrap()
.trim()
.to_string()
// "(25x3)(3x3)ABC(2x3)XY(5x2)PQRSTX(18x9)(3x2)TWO(5x7)SEVEN".to_string()
}
|
