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
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
|
// [nix-shell:~/projects/sandbox/advent]$ cargo run --bin 12
// Compiling advent v0.1.0 (/home/orbekk/projects/sandbox/advent)
// Finished dev [unoptimized + debuginfo] target(s) in 0.40s
// Running `target/debug/12`
// After 10 steps:
// pos=<x= 2, y= 1, z= -3>, vel=<x= -3, y= -2, z= 1>
// pos=<x= 1, y= -8, z= 0>, vel=<x= -1, y= 1, z= 3>
// pos=<x= 3, y= -6, z= 1>, vel=<x= 3, y= 2, z= -3>
// pos=<x= 2, y= 0, z= 4>, vel=<x= 1, y= -1, z= -1>
//
// energy=179
//
// After 1000 steps:
// pos=<x=-26, y= 45, z=-31>, vel=<x= 2, y= 17, z= 6>
// pos=<x= 87, y= 23, z=-12>, vel=<x=-14, y=-13, z= 9>
// pos=<x=-33, y= -2, z=-24>, vel=<x= -2, y=-15, z= -5>
// pos=<x=-20, y=-86, z= 77>, vel=<x= 14, y= 11, z=-10>
//
// energy=14645
use std::fmt;
#[derive(Debug)]
struct Moon {
position: (i64, i64, i64),
velocity: (i64, i64, i64),
}
fn sign(x: i64) -> i64 {
if x < 0 {
-1
} else if x > 0 {
1
} else {
0
}
}
impl Moon {
fn step(&self, moons: &Vec<Moon>) -> Moon {
let (x, y, z) = self.position;
let (mut gx, mut gy, mut gz) = self.velocity;
for moon in moons {
let (ox, oy, oz) = moon.position;
gx += sign(ox - x);
gy += sign(oy - y);
gz += sign(oz - z);
}
let position = (x + gx, y + gy, z + gz);
Moon { position: position, velocity: (gx, gy, gz) }
}
fn energy(&self) -> i64 {
let (x, y, z) = self.position;
let (p, q, r) = self.velocity;
(x.abs() + y.abs() + z.abs()) * (p.abs() + q.abs() + r.abs())
}
}
fn make_moon(x: i64, y: i64, z: i64) -> Moon {
Moon { position: (x, y, z), velocity: (0, 0, 0) }
}
impl fmt::Display for Moon {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
let (x, y, z) = self.position;
let (p, q, r) = self.velocity;
write!(f, "pos=<x={:3}, y={:3}, z={:3}>, vel=<x={:3}, y={:3}, z={:3}>",
x, y, z, p, q, r)
}
}
#[derive(Debug)]
struct Moons(Vec<Moon>);
impl Moons {
fn step(&self) -> Moons {
Moons(self.0.iter().map(|m| m.step(&self.0)).collect())
}
fn energy(&self) -> i64 {
self.0.iter().map(|m| m.energy()).sum()
}
}
impl fmt::Display for Moons {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
for moon in &self.0 {
moon.fmt(f)?;
write!(f, "\n")?;
}
Ok(())
}
}
fn run_steps(mut m: Moons, steps: i64, debug: bool) {
for i in 0..steps {
if debug {
println!("After {} steps:", i);
println!("{}", m);
}
m = m.step()
}
println!("After {} steps:", steps);
println!("{}", m);
println!("energy={:3}", m.energy())
}
fn main() {
let _ex1 = Moons(vec!(
make_moon(-1, 0, 2),
make_moon(2, -10, -7),
make_moon(4, -8, 8),
make_moon(3, 5, -1),
));
let _ex2 = Moons(vec!(
make_moon(-8, -10, 0),
make_moon(5, 5, 10),
make_moon(2, -7, 3),
make_moon(9, -8, -3),
));
let _ex3 = Moons(vec!(
make_moon(-1, 7, 3),
make_moon(12, 2, -13),
make_moon(14, 18, -8),
make_moon(17, 4, -4),
));
run_steps(_ex1, 10, false);
println!();
run_steps(_ex3, 1000, false);
}
|
