blob: f61c09dca9e9945e89940cb96edaa5c3b48a8d56 (
plain)
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
|
use std::collections::{HashSet};
use std::io::{BufRead};
fn main() {
let stdin = std::io::stdin();
let mut handle = stdin.lock();
let mut buf: Vec<u8> = Vec::new();
let mut seen: HashSet<[isize; 2]> = HashSet::new();
let mut head_pos: [isize; 2] = [0; 2];
let mut tail_pos: [isize; 2] = head_pos.clone();
seen.insert(tail_pos.clone());
loop {
buf.clear();
let num_bytes = handle.read_until(b'\n', &mut buf).expect("IO error");
if num_bytes == 0 { break; }
if buf[buf.len() - 1] == b'\n' { buf.pop(); }
let direction = buf[0];
let num_steps: usize = std::str::from_utf8(& buf[2..]).expect("Malformed input")
.parse().expect("Malformed input");
for dir in std::iter::repeat(direction).take(num_steps) {
match dir {
b'L' => head_pos[0] -= 1,
b'R' => head_pos[0] += 1,
b'U' => head_pos[1] += 1,
b'D' => head_pos[1] -= 1,
_ => panic!("Malformed input")
};
let delta: [isize; 2] = {
let mut ret: [isize; 2] = [0; 2];
for i in 0..2 { ret[i] = head_pos[i] - tail_pos[i]; }
ret
};
if delta[0].abs() == 2 {
tail_pos[0] += delta[0].signum();
if delta[1].abs() == 1 {
tail_pos[1] += delta[1].signum();
}
seen.insert(tail_pos.clone());
}
else if delta[1].abs() == 2 {
tail_pos[1] += delta[1].signum();
if delta[0].abs() == 1 {
tail_pos[0] += delta[0].signum();
}
seen.insert(tail_pos.clone());
}
}
}
println!("{}", seen.len());
}
|
