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
|
#![allow(
clippy::many_single_char_names, clippy::deref_addrof, clippy::unreadable_literal, clippy::many_single_char_names
)]
use ndarray::prelude::*;
const INPUT: &[u8] = include_bytes!("life.txt");
const N: usize = 100;
type Board = Array2<u8>;
fn parse(x: &[u8]) -> Board
{
// make a border of 0 cells
let mut map = Board::from_elem(((N + 2), (N + 2)), 0);
let a = Array::from_iter(x.iter().filter_map(|&b| match b {
b'#' => Some(1),
b'.' => Some(0),
_ => None,
}));
let a = a.into_shape_with_order((N, N)).unwrap();
map.slice_mut(s![1..-1, 1..-1]).assign(&a);
map
}
// Rules
//
// 2 or 3 neighbors: stay alive
// 3 neighbors: birth
// otherwise: death
fn iterate(z: &mut Board, scratch: &mut Board)
{
// compute number of neighbors
let mut neigh = scratch.view_mut();
neigh.fill(0);
neigh += &z.slice(s![0..-2, 0..-2]);
neigh += &z.slice(s![0..-2, 1..-1]);
neigh += &z.slice(s![0..-2, 2..]);
neigh += &z.slice(s![1..-1, 0..-2]);
neigh += &z.slice(s![1..-1, 2..]);
neigh += &z.slice(s![2.., 0..-2]);
neigh += &z.slice(s![2.., 1..-1]);
neigh += &z.slice(s![2.., 2..]);
// birth where n = 3 and z[i] = 0,
// survive where n = 2 || n = 3 and z[i] = 1
let mut zv = z.slice_mut(s![1..-1, 1..-1]);
// this is autovectorized amazingly well!
zv.zip_mut_with(&neigh, |y, &n| *y = ((n == 3) || (n == 2 && *y > 0)) as u8);
}
fn turn_on_corners(z: &mut Board)
{
let n = z.nrows();
let m = z.ncols();
z[[1, 1]] = 1;
z[[1, m - 2]] = 1;
z[[n - 2, 1]] = 1;
z[[n - 2, m - 2]] = 1;
}
fn render(a: &Board)
{
for row in a.rows() {
for &x in row {
if x > 0 {
print!("#");
} else {
print!(".");
}
}
println!();
}
}
fn main()
{
let mut a = parse(INPUT);
let mut scratch = Board::zeros((N, N));
let steps = 100;
turn_on_corners(&mut a);
for _ in 0..steps {
iterate(&mut a, &mut scratch);
turn_on_corners(&mut a);
//render(&a);
}
render(&a);
let alive = a.iter().filter(|&&x| x > 0).count();
println!("After {} steps there are {} cells alive", steps, alive);
}
|
