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Precompute only 2char masks

This commit is contained in:
Luke Hubmayer-Werner 2022-12-07 14:10:58 +10:30
parent 0c432507a7
commit 33a79a23bc
1 changed files with 13 additions and 12 deletions
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25
2022/day6.rs
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@ -41,25 +41,26 @@ fn find_first_unique_runs(s: &Vec<u8>) -> (Int, Int) {
for i in 0..4096 {
masks[i] = 1 << (s[i]-b'a');
}
let mut m: [u32; 4096] = masks.clone();
for n in 1..4 {
for i in n..4096 {
m[i] |= masks[i-n];
}
let mut masks2: [u32; 4096] = masks.clone();
for i in 1..4096 {
masks2[i] |= masks[i-1];
}
for i in 4..4096 {
if m[i].count_ones() == 4 {
// 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;
}
}
for n in 4..14 {
for i in n..4096 {
m[i] |= masks[i-n];
}
}
for i in (four+9)..4096 {
if m[i].count_ones() == 14 {
// 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;
}