-
Notifications
You must be signed in to change notification settings - Fork 0
/
14.rs
112 lines (101 loc) · 2.6 KB
/
14.rs
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
use std::collections::HashMap;
static INPUT_TXT: &str = include_str!("../../input/14.txt");
fn main() {
println!("Part 1: {}", part_1(INPUT_TXT));
println!("Part 2: {}", part_2(INPUT_TXT));
}
fn parse_input(input: &str) -> Vec<Vec<char>> {
input
.trim()
.lines()
.map(|line| line.chars().collect())
.collect()
}
fn part_1(input: &str) -> usize {
let grid = parse_input(input);
(0..grid[0].len()).fold(0, |mut total, col| {
(0..grid.len()).fold(0, |next, row| match grid[row].get(col) {
Some('O') => {
total += grid.len() - next;
next + 1
}
Some('#') => row + 1,
_ => next,
});
total
})
}
fn roll_north(mut grid: Vec<Vec<char>>) -> Vec<Vec<char>> {
loop {
let mut done = true;
for row in 0..grid.len() - 1 {
for col in 0..grid[row].len() {
if grid[row + 1][col] == 'O' && grid[row][col] == '.' {
grid[row][col] = 'O';
grid[row + 1][col] = '.';
done = false;
}
}
}
if done {
break grid;
}
}
}
fn rotate(grid: &[Vec<char>]) -> Vec<Vec<char>> {
grid.iter().enumerate().fold(
vec![vec!['.'; grid.len()]; grid[0].len()],
|mut newgrid, (r, row)| {
for (c, &char) in row.iter().enumerate() {
newgrid[c][grid.len() - 1 - r] = char;
}
newgrid
},
)
}
fn part_2(input: &str) -> usize {
let mut grid = parse_input(input);
let mut seen = HashMap::new();
for i in 1..1_000_000_000 {
grid = (0..4).fold(grid, |grid, _| rotate(&roll_north(grid)));
if let Some(seen_at) = seen.insert(grid.clone(), i) {
if (1_000_000_000 - i) % (i - seen_at) == 0 {
break;
}
}
}
grid.iter()
.enumerate()
.map(|(height, row)| {
row.iter()
.enumerate()
.filter(|&(_, &c)| c == 'O')
.map(|_| grid.len() - height)
.sum::<usize>()
})
.sum()
}
#[cfg(test)]
mod tests {
use super::*;
static INPUT: &str = "O....#....
O.OO#....#
.....##...
OO.#O....O
.O.....O#.
O.#..O.#.#
..O..#O..O
.......O..
#....###..
#OO..#....";
#[test]
fn test_part_1() {
assert_eq!(part_1(INPUT), 136);
assert_eq!(part_1(INPUT_TXT), 106_186);
}
#[test]
fn test_part_2() {
assert_eq!(part_2(INPUT), 64);
assert_eq!(part_2(INPUT_TXT), 106_390);
}
}