Revert "Use jump table"

This reverts commit c8f5182.

Author: EbbDrop

build.rs

@@ -225,36 +225,38 @@ fn write_day21() {
     file.write_all(&lut).unwrap();
 }
 
-#[allow(unused)]
-fn write_day22() {
-    const MAX: u32 = 16777216;
+// #[allow(unused)]
+// fn write_day22() {
+//     const MAX: u32 = 16777216;
 
-    let mut lut = Vec::with_capacity(MAX as usize);
+//     let mut lut = Vec::with_capacity(MAX as usize);
 
-    for i in 0..MAX {
-        let mut sn = i;
-        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;
+//     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);
-    }
+//         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 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_jmp.bin");
-    let mut file = File::create(&path).unwrap();
+//     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());
-}
+//     file.write_all(lut.as_slice()).unwrap();
+//     println!("{}", path.display());
+// }
 
 fn main() {
     println!("cargo::rerun-if-changed=build.rs");
 
     write_day21();
-    write_day22();
+    // write_day22();
 }

src/day22.rs

@@ -44,9 +44,6 @@ pub fn part1(s: &str) -> u64 {
     sum
 }
 
-static JMP_TBL: [u32; MAX as usize] =
-    unsafe { transmute(*include_bytes!(concat!(env!("OUT_DIR"), "/day22_jmp.bin"))) };
-
 const SEQUENCES: usize = 18 * 18 * 18 * 18;
 
 #[aoc(day22, part2)]
@@ -86,7 +83,9 @@ pub fn part2(s: &str) -> i16 {
             let mut prev = sn % 10;
 
             for _ in 0..3 {
-                sn = JMP_TBL[sn as usize];
+                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;
                 let price = sn % 10;
                 let diff = price + 9 - prev;
                 diffs = diffs * 18 + diff;
@@ -95,7 +94,9 @@ pub fn part2(s: &str) -> i16 {
             }
 
             for _ in 4..2000 {
-                sn = JMP_TBL[sn as usize];
+                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;
                 let price = sn % 10;
                 let diff = price + 9 - prev;
                 diffs = (diffs * 18 + diff) % SEQUENCES as u32;