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caching meme for D17 to save time

This commit is contained in:
kageru 2021-07-08 23:58:57 +02:00
parent a570cf6fda
commit adb0e84858
Signed by: kageru
GPG Key ID: 8282A2BEA4ADA3D2
1 changed files with 47 additions and 0 deletions
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47
2020/src/grid/position.rs
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@ -1,5 +1,6 @@
extern crate test;
use super::direction::*;
use lazy_static::lazy_static;
use std::{
convert::TryInto, hash::Hash, ops::{Add, Mul, Sub}
};
@ -55,6 +56,40 @@ impl<const DIMS: usize> PositionND<DIMS> {
pub fn neighbors(&self) -> [PositionND<DIMS>; num_neighbors(DIMS)]
where [PositionND<DIMS>; num_neighbors(DIMS) + 1]: Sized {
// Day 17 gets 25% faster if we cheat by using these cached vectors
if DIMS < 5 {
return match DIMS {
1 => {
let mut out = [*self; num_neighbors(DIMS)];
for (out, dir) in out.iter_mut().zip(NEIGHBOR_VECTORS_1D.iter()) {
*out = *out + PositionND::from_padded(dir);
}
out
}
2 => {
let mut out = [*self; num_neighbors(DIMS)];
for (out, dir) in out.iter_mut().zip(NEIGHBOR_VECTORS_2D.iter()) {
*out = *out + PositionND::from_padded(dir);
}
out
}
3 => {
let mut out = [*self; num_neighbors(DIMS)];
for (out, dir) in out.iter_mut().zip(NEIGHBOR_VECTORS_3D.iter()) {
*out = *out + PositionND::from_padded(dir);
}
out
}
4 => {
let mut out = [*self; num_neighbors(DIMS)];
for (out, dir) in out.iter_mut().zip(NEIGHBOR_VECTORS_4D.iter()) {
*out = *out + PositionND::from_padded(dir);
}
out
}
_ => unreachable!(),
};
}
let ns = neighbor_vectors::<DIMS>();
let mut out = [*self; num_neighbors(DIMS)];
for (out, dir) in out.iter_mut().zip(IntoIterator::into_iter(ns).filter(|n| n != &[0; DIMS])) {
@ -64,6 +99,18 @@ impl<const DIMS: usize> PositionND<DIMS> {
}
}
fn build_neighbor_cache<const D: usize>() -> Vec<[i64; D]>
where [(); num_neighbors(D) + 1]: {
IntoIterator::into_iter(neighbor_vectors::<D>()).filter(|n| n != &[0; D]).collect()
}
lazy_static! {
static ref NEIGHBOR_VECTORS_1D: Vec<[i64; 1]> = build_neighbor_cache::<1>();
static ref NEIGHBOR_VECTORS_2D: Vec<[i64; 2]> = build_neighbor_cache::<2>();
static ref NEIGHBOR_VECTORS_3D: Vec<[i64; 3]> = build_neighbor_cache::<3>();
static ref NEIGHBOR_VECTORS_4D: Vec<[i64; 4]> = build_neighbor_cache::<4>();
}
#[macro_export]
macro_rules! dim {
($d: expr) => {{