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
|
use std::io::Read;
use std::fs::File;
#[derive(Clone, Copy, Debug)]
enum Direction {
Up,
Left,
Down,
Right
}
impl Direction {
fn turn_right(self) -> Direction {
match self {
Direction::Up => Direction::Right,
Direction::Right => Direction::Down,
Direction::Down => Direction::Left,
Direction::Left => Direction::Up
}
}
fn turn_left(self) -> Direction {
//not an ambiturner
self.turn_right().turn_right().turn_right()
}
fn as_vector(self, dist: i32) -> (i32,i32) {
match self {
Direction::Up => (0, -dist),
Direction::Right => (dist, 0),
Direction::Down => (0, dist),
Direction::Left => (-dist, 0)
}
}
}
fn main() {
let content = read_file().expect("Failed to read file");
let (_, dist_x, dist_y) = first_repeated_dest(content);
println!("Total: ({}, {})", dist_x, dist_y);
println!("Net: {}", dist_x+dist_y);
}
fn net_distance(content: String) -> (Direction, i32, i32) {
content.trim().split(", ")
.map(|action|
(
action.chars().nth(0).unwrap(),
action.chars().skip(1).collect::<String>().parse::<i32>().unwrap()
))
.fold((Direction::Up, 0,0), |(facing, acc_x, acc_y), (dir, dist)| {
let new_facing = match dir {
'R' => facing.turn_right(),
'L' => facing.turn_left(),
_ => panic!("bad input")
};
let (new_x, new_y) = new_facing.as_vector(dist);
(new_facing, acc_x+new_x, acc_y+new_y)
})
}
fn first_repeated_dest(content: String) -> (Direction, i32, i32) {
let mut stops: Vec<(i32, i32)> = Vec::new();
let actions = content.trim().split(", ")
.map(|action|
(
action.chars().nth(0).unwrap(),
action.chars().skip(1).collect::<String>().parse::<i32>().unwrap()
));
let mut current_facing = Direction::Up;
let (mut acc_x, mut acc_y) = (0, 0);
for (dir, dist) in actions {
current_facing = match dir {
'R' => current_facing.turn_right(),
'L' => current_facing.turn_left(),
_ => panic!("bad input")
};
for _ in 0..dist {
let (new_x, new_y) = current_facing.as_vector(1);
acc_x += new_x;
acc_y += new_y;
if stops.iter().any(|&(x, y)| x==acc_x && y==acc_y) {
return (current_facing, acc_x, acc_y);
}
stops.push((acc_x, acc_y));
}
}
(current_facing, acc_x, acc_y)
}
fn read_file() -> Result<String, String> {
let mut file = try!(File::open("input.txt").map_err(|e| e.to_string()));
let mut content = String::new();
try!(file.read_to_string(&mut content).map_err(|e| e.to_string()));
Ok(content)
}
|
