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bitmask batching

This commit is contained in:
Luke Hubmayer-Werner 2022-12-07 15:11:23 +10:30
parent 33a79a23bc
commit 253068d67d
1 changed files with 41 additions and 22 deletions
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63
2022/day6.rs
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@ -35,37 +35,56 @@ fn mask_to_string(mask: u32) -> String {
}
fn find_first_unique_runs(s: &Vec<u8>) -> (Int, Int) {
let mut four = 0;
let mut fourteen = 0;
const BATCH_SIZE: Int = 8;
const BATCH_NUM: Int = 4096/BATCH_SIZE;
let mut four: Int = 0;
let mut fourteen: Int = 0;
let mut masks: [u32; 4096] = [0; 4096];
let mut scratch_masks: [u32; BATCH_SIZE] = [0; BATCH_SIZE];
let mut scratch_masks_bits: [u8; BATCH_SIZE] = [0; BATCH_SIZE];
for i in 0..4096 {
masks[i] = 1 << (s[i]-b'a');
}
let mut masks2: [u32; 4096] = masks.clone();
for i in 1..4096 {
masks2[i] |= masks[i-1];
// Turn masks into masks2. Indices are now +1.
for i in 0..(4096-1) {
masks[i] |= masks[i+1];
}
for i in 4..4096 {
// let mut mask = masks[i];
// for j in 1..4 {mask |= masks[i-j];}
let mut mask = masks2[i];
for j in 1..2 {mask |= masks2[i-j*2];}
if mask.count_ones() == 4 {
four = i;
break;
'four_loop: for batch in 1..(BATCH_NUM) {
for i in 0..BATCH_SIZE {
let idx = batch*BATCH_SIZE + i;
scratch_masks[i] = masks[idx] | masks[idx-2];
scratch_masks_bits[i] = scratch_masks[i].count_ones() as u8;
}
for i in 0..BATCH_SIZE {
if scratch_masks_bits[i] == 4 {
four = batch*BATCH_SIZE + i;
break 'four_loop;
}
}
}
for i in (four+9)..4096 {
// let mut mask = masks[i];
// for j in 1..14 {mask |= masks[i-j];}
let mut mask = masks2[i];
for j in 1..7 {mask |= masks2[i-j*2];} // (2..14).step_by(2) doesn't unroll, LLVM is garbage
if mask.count_ones() == 14 {
fourteen = i;
break;
// Turn masks2 into masks4. Indices are now +3.
for i in four..(4096-3) {
masks[i] |= masks[i+2];
}
// Turn masks4 into masks8. Indices are now +7.
for i in four..(4096-7) {
masks[i] |= masks[i+4];
}
'fourteen_loop: for batch in (four/BATCH_SIZE)..(BATCH_NUM) {
for i in 0..BATCH_SIZE {
let idx = batch*BATCH_SIZE + i;
// scratch_masks[i] = masks[idx] | masks[idx-4] | masks[idx-8] | masks[idx-10];
scratch_masks[i] = masks[idx] | masks[idx-6];
scratch_masks_bits[i] = scratch_masks[i].count_ones() as u8;
}
for i in 0..BATCH_SIZE {
if scratch_masks_bits[i] == 14 {
fourteen = batch*BATCH_SIZE + i;
break 'fourteen_loop;
}
}
}
return (four+1, fourteen+1);
return (four+2, fourteen+8);
}
fn run_once(s: &Vec<u8>) {