Add day22 lut

Author: EbbDrop

build.rs

@@ -225,8 +225,38 @@ fn write_day21() {
     file.write_all(&lut).unwrap();
 }
 
+// #[allow(unused)]
+// fn write_day22() {
+//     const MAX: u32 = 16777216;
+
+//     let mut lut = Vec::with_capacity(MAX as usize);
+
+//     for i in 0..MAX {
+//         let mut sn = i;
+//         for _ in 0..2000 {
+//             sn = ((sn as u64 * 64) % MAX as u64) as u32 ^ sn;
+//             sn = (sn / 32) ^ sn;
+//             sn = ((sn as u64 * 2048) % MAX as u64) as u32 ^ sn;
+//         }
+
+//         lut.push(sn);
+//     }
+
+//     let lut: Box<[u32; MAX as usize]> = lut.into_boxed_slice().try_into().unwrap();
+//     let mut lut = std::mem::ManuallyDrop::new(lut);
+//     let lut: Box<[u8; 4 * MAX as usize]> = unsafe { Box::from_raw(lut.as_mut_ptr().cast()) };
+
+//     let mut path = PathBuf::from(std::env::var("OUT_DIR").unwrap());
+//     path.push("day22.bin");
+//     let mut file = File::create(&path).unwrap();
+
+//     file.write_all(lut.as_slice()).unwrap();
+//     println!("{}", path.display());
+// }
+
 fn main() {
     println!("cargo::rerun-if-changed=build.rs");
 
     write_day21();
+    // write_day22();
 }

day22_lut.bin

@@ -1,11 +1,11 @@
 use core::str;
+use std::mem::transmute;
 
 use aoc_runner_derive::aoc;
 
 const MAX: u32 = 16777216;
 
-// static LUT_P1: [u32; MAX as usize] =
-//     unsafe { transmute(*include_bytes!(concat!(env!("OUT_DIR"), "/day22.bin"))) };
+static LUT_P1: [u32; MAX as usize] = unsafe { transmute(*include_bytes!("../day22_lut.bin")) };
 
 #[aoc(day22, part1)]
 pub fn part1(s: &str) -> u64 {
@@ -37,13 +37,7 @@ pub fn part1(s: &str) -> u64 {
             }
             i += 1;
 
-            for _ in 0..2000 {
-                sn = ((sn as u64 * 64) % MAX as u64) as u32 ^ sn;
-                sn = (sn / 32) ^ sn;
-                sn = ((sn as u64 * 2048) % MAX as u64) as u32 ^ sn;
-            }
-
-            sum += sn as u64;
+            sum += LUT_P1[sn as usize] as u64;
         }
     }
 
@@ -87,6 +81,7 @@ pub fn part2(s: &str) -> i16 {
 
             let mut diffs = 0;
             let mut prev = sn % 10;
+
             for _ in 0..3 {
                 sn = ((sn as u64 * 64) % MAX as u64) as u32 ^ sn;
                 sn = (sn / 32) ^ sn;