blob: a9410f2587dd4b152f7ec2f3bfccafedfda9a02b (
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
60
61
62
|
use std::fs;
fn solve_puzzle(first: &str, num_rows: usize) -> usize {
let mut total = first.matches('.').count();
let mut tiles: Vec<char> = first.chars().collect();
for _i in 1..num_rows {
let mut next = Vec::new();
for j in 0..tiles.len() {
let is_trap;
// At left wall
if j == 0 {
is_trap = tiles[j + 1] == '^'; // rule 2 + 4
// At right wall
} else if j == tiles.len() - 1 {
is_trap = tiles[j - 1] == '^'; // rule 1 + 3
// Away from the walls
} else {
is_trap = tiles[j - 1] == '^' && tiles[j + 1] == '.' // rule 1 + 3
|| tiles[j - 1] == '.' && tiles[j + 1] == '^'; // rule 2 + 4
}
next.push(if is_trap { '^' } else { '.' });
}
tiles = next;
total += tiles.iter().filter(|&c| *c == '.').count();
}
total
}
fn main() {
// Read my personal puzzle input
let input = fs::read_to_string("input.txt").unwrap();
let first = input.trim_end();
// Part 1 gives 1939 for me
println!("Part 1 solution: {}", solve_puzzle(first, 40));
// Part 2 gives 19999535 for me
println!("Part 1 solution: {}", solve_puzzle(first, 400000));
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn part1_example1() {
let input = "..^^.";
assert_eq!(solve_puzzle(input, 3), 6);
}
#[test]
fn part1_example2() {
let input = ".^^.^.^^^^";
assert_eq!(solve_puzzle(input, 10), 38);
}
}
|
