54 lines
1.2 KiB
Rust
54 lines
1.2 KiB
Rust
use std::collections::HashMap;
|
|
|
|
const INPUT: &str = include_str!("../../data/day15");
|
|
|
|
struct Memory {
|
|
turn: usize,
|
|
mem: HashMap<usize, usize>,
|
|
previous: usize,
|
|
}
|
|
|
|
impl Memory {
|
|
fn new() -> Self {
|
|
Self {
|
|
turn: 0,
|
|
mem: HashMap::new(),
|
|
previous: 0,
|
|
}
|
|
}
|
|
|
|
fn remember(&mut self, value: usize) {
|
|
if self.turn > 0 {
|
|
self.mem.insert(self.previous, self.turn);
|
|
}
|
|
self.turn += 1;
|
|
self.previous = value;
|
|
}
|
|
}
|
|
|
|
fn main() {
|
|
let input: Vec<usize> = INPUT.trim().split(",").map(|s| s.parse().unwrap()).collect();
|
|
let mut mem = Memory::new();
|
|
for &value in &input {
|
|
mem.remember(value);
|
|
}
|
|
while mem.turn < 2020 {
|
|
let value = mem.previous;
|
|
if let Some(&turn) = mem.mem.get(&value) {
|
|
mem.remember(mem.turn - turn);
|
|
} else {
|
|
mem.remember(0);
|
|
}
|
|
}
|
|
println!("{}", mem.previous);
|
|
while mem.turn < 30000000 {
|
|
let value = mem.previous;
|
|
if let Some(&turn) = mem.mem.get(&value) {
|
|
mem.remember(mem.turn - turn);
|
|
} else {
|
|
mem.remember(0);
|
|
}
|
|
}
|
|
println!("{}", mem.previous);
|
|
}
|