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day 13 optimizations. turns out that being clever was bad today
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@kcaffrey
kcaffrey committed Dec 13, 2023
1 parent cf6f147 commit e0b243f
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30 changes: 15 additions & 15 deletions README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -29,21 +29,21 @@ Solutions for [Advent of Code](https://adventofcode.com/) in [Rust](https://www.

| Day | Part 1 | Part 2 |
| :---: | :---: | :---: |
| [Day 1](./src/bin/01.rs) | `27.6µs` | `39.7µs` |
| [Day 2](./src/bin/02.rs) | `43.1µs` | `42.7µs` |
| [Day 3](./src/bin/03.rs) | `83.8µs` | `100.4µs` |
| [Day 4](./src/bin/04.rs) | `48.4µs` | `51.9µs` |
| [Day 5](./src/bin/05.rs) | `20.8µs` | `24.2µs` |
| [Day 6](./src/bin/06.rs) | `202.0ns` | `102.0ns` |
| [Day 7](./src/bin/07.rs) | `94.4µs` | `94.2µs` |
| [Day 8](./src/bin/08.rs) | `75.3µs` | `160.8µs` |
| [Day 9](./src/bin/09.rs) | `58.2µs` | `58.3µs` |
| [Day 10](./src/bin/10.rs) | `262.3µs` | `274.2µs` |
| [Day 11](./src/bin/11.rs) | `16.4µs` | `16.0µs` |
| [Day 12](./src/bin/12.rs) | `132.6µs` | `678.2µs` |
| [Day 13](./src/bin/13.rs) | `66.9µs` | `66.9µs` |

**Total: 2.54ms**
| [Day 1](./src/bin/01.rs) | `28.7µs` | `36.3µs` |
| [Day 2](./src/bin/02.rs) | `42.5µs` | `42.0µs` |
| [Day 3](./src/bin/03.rs) | `84.3µs` | `99.5µs` |
| [Day 4](./src/bin/04.rs) | `48.1µs` | `50.9µs` |
| [Day 5](./src/bin/05.rs) | `20.7µs` | `24.4µs` |
| [Day 6](./src/bin/06.rs) | `205.0ns` | `102.0ns` |
| [Day 7](./src/bin/07.rs) | `93.9µs` | `92.7µs` |
| [Day 8](./src/bin/08.rs) | `75.1µs` | `159.3µs` |
| [Day 9](./src/bin/09.rs) | `58.9µs` | `58.4µs` |
| [Day 10](./src/bin/10.rs) | `257.9µs` | `275.7µs` |
| [Day 11](./src/bin/11.rs) | `16.5µs` | `15.8µs` |
| [Day 12](./src/bin/12.rs) | `135.9µs` | `647.1µs` |
| [Day 13](./src/bin/13.rs) | `12.4µs` | `40.5µs` |

**Total: 2.42ms**
<!--- benchmarking table --->

---
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88 changes: 42 additions & 46 deletions src/bin/13.rs
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Original file line number Diff line number Diff line change
@@ -1,41 +1,37 @@
use smallvec::SmallVec;

advent_of_code::solution!(13);

pub fn part_one(input: &str) -> Option<u32> {
Some(
input
.split("\n\n")
.map(|pattern| {
let mut row_values = SmallVec::<[u32; 32]>::new();
let mut col_values = SmallVec::<[u32; 32]>::new();
for line in pattern.lines() {
let mut row_encoded = 0;
if col_values.is_empty() {
col_values.resize(line.len(), 0);
}
for (col, ch) in line.char_indices() {
let encoded_val = if ch == '#' { 1 } else { 0 };
col_values[col] = (col_values[col] << 1) + encoded_val;
row_encoded = (row_encoded << 1) + encoded_val;
}
row_values.push(row_encoded);
}
let pattern = pattern.as_bytes();
let cols = pattern
.iter()
.position(|&ch| ch == b'\n')
.expect("should be more than one row");
let rows = (pattern.len() + 1) / (cols + 1);

// Try column mirroring.
let col_mirror = (1..col_values.len()).find(|&col_split| {
(0..col_split.min(col_values.len() - col_split)).all(|offset| {
col_values[col_split - offset - 1] == col_values[col_split + offset]
let col_mirror = (1..cols).find(|&col_split| {
(0..col_split.min(cols - col_split)).all(|offset| {
(0..rows).all(|r| {
pattern[r * (cols + 1) + col_split - offset - 1]
== pattern[r * (cols + 1) + col_split + offset]
})
})
});
if let Some(col_mirror) = col_mirror {
return col_mirror as u32;
}

// Try row mirroring.
let row_mirror = (1..row_values.len()).find(|&row_split| {
(0..row_split.min(row_values.len() - row_split)).all(|offset| {
row_values[row_split - offset - 1] == row_values[row_split + offset]
let row_mirror = (1..rows).find(|&row_split| {
(0..row_split.min(rows - row_split)).all(|offset| {
(0..cols).all(|c| {
pattern[(row_split - offset - 1) * (cols + 1) + c]
== pattern[(row_split + offset) * (cols + 1) + c]
})
})
});
if let Some(row_mirror) = row_mirror {
Expand All @@ -53,27 +49,23 @@ pub fn part_two(input: &str) -> Option<u32> {
input
.split("\n\n")
.map(|pattern| {
let mut row_values = SmallVec::<[u32; 32]>::new();
let mut col_values = SmallVec::<[u32; 32]>::new();
for line in pattern.lines() {
let mut row_encoded = 0u32;
if col_values.is_empty() {
col_values.resize(line.len(), 0u32);
}
for (col, ch) in line.char_indices() {
let encoded_val = if ch == '#' { 1 } else { 0 };
col_values[col] = (col_values[col] << 1) + encoded_val;
row_encoded = (row_encoded << 1) + encoded_val;
}
row_values.push(row_encoded);
}
let pattern = pattern.as_bytes();
let cols = pattern
.iter()
.position(|&ch| ch == b'\n')
.expect("should be more than one row");
let rows = (pattern.len() + 1) / (cols + 1);

// Try column mirroring.
let col_mirror = (1..col_values.len()).find(|&col_split| {
(0..col_split.min(col_values.len() - col_split))
let col_mirror = (1..cols).find(|&col_split| {
(0..col_split.min(cols - col_split))
.map(|offset| {
(col_values[col_split - offset - 1] ^ col_values[col_split + offset])
.count_ones()
(0..rows)
.map(|r| -> u32 {
(pattern[r * (cols + 1) + col_split - offset - 1]
!= pattern[r * (cols + 1) + col_split + offset])
.into()
})
.sum::<u32>()
})
.sum::<u32>()
== 1
Expand All @@ -82,12 +74,16 @@ pub fn part_two(input: &str) -> Option<u32> {
return col_mirror as u32;
}

// Try row mirroring.
let row_mirror = (1..row_values.len()).find(|&row_split| {
(0..row_split.min(row_values.len() - row_split))
let row_mirror = (1..rows).find(|&row_split| {
(0..row_split.min(rows - row_split))
.map(|offset| {
(row_values[row_split - offset - 1] ^ row_values[row_split + offset])
.count_ones()
(0..cols)
.map(|c| -> u32 {
(pattern[(row_split - offset - 1) * (cols + 1) + c]
!= pattern[(row_split + offset) * (cols + 1) + c])
.into()
})
.sum::<u32>()
})
.sum::<u32>()
== 1
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