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Replace regex with aho-corasick

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Bert Peters
2023-12-02 13:44:07 +01:00
parent 2a419bb468
commit 5517662ae2
2 changed files with 19 additions and 27 deletions
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2
2023/Cargo.toml
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@@ -6,10 +6,10 @@ edition = "2021"
# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
[dependencies] [dependencies]
aho-corasick = "1.1.2"
anyhow = "1.0.75" anyhow = "1.0.75"
clap = { version = "4.4.8", features = ["derive"] } clap = { version = "4.4.8", features = ["derive"] }
nom = "7.1.3" nom = "7.1.3"
regex = "1.10.2"
[dev-dependencies] [dev-dependencies]
criterion = "0.5.1" criterion = "0.5.1"

40
2023/src/day01.rs
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@@ -1,5 +1,5 @@
use aho_corasick::AhoCorasick;
use anyhow::Result; use anyhow::Result;
use regex::bytes::Regex;
pub fn part1(input: &[u8]) -> Result<String> { pub fn part1(input: &[u8]) -> Result<String> {
let mut it = input.iter(); let mut it = input.iter();
@@ -22,43 +22,35 @@ pub fn part1(input: &[u8]) -> Result<String> {
Ok(sum.to_string()) Ok(sum.to_string())
} }
fn parse_string_digit(digit: &[u8]) -> Result<u32> { pub fn part2(input: &[u8]) -> Result<String> {
Ok(match digit { let parser = AhoCorasick::new([
b"one" => 1, "1", "2", "3", "4", "5", "6", "7", "8", "9", "one", "two", "three", "four", "five", "six",
b"two" => 2, "seven", "eight", "nine",
b"three" => 3, ])?;
b"four" => 4,
b"five" => 5, fn convert_id(id: u32) -> Result<u32> {
b"six" => 6, Ok(match id {
b"seven" => 7, 0..=8 => id + 1,
b"eight" => 8, 9..=17 => id - 8,
b"nine" => 9, _ => anyhow::bail!("unreachable"),
&[d] => u32::from(d - b'0'),
other => anyhow::bail!("invalid digit: {}", String::from_utf8_lossy(other)),
}) })
} }
// 53255: too low
pub fn part2(input: &[u8]) -> Result<String> {
let parser = Regex::new(r"[1-9]|one|two|three|four|five|six|seven|eight|nine")?;
let mut sum = 0; let mut sum = 0;
for line in input.split(|&c| c == b'\n') { for line in input.split(|&c| c == b'\n') {
let mut first = None; let mut first = None;
let mut last = &b""[..]; let mut last = 0;
let mut start = 0;
// Cannot use find_iter because it doesn't find overlapping matches. // Cannot use find_iter because it doesn't find overlapping matches.
while let Some(needle) = parser.find_at(line, start) { for needle in parser.find_overlapping_iter(line) {
start = needle.start() + 1; let digit = convert_id(needle.pattern().as_u32())?;
let digit = needle.as_bytes();
first.get_or_insert(digit); first.get_or_insert(digit);
last = digit; last = digit;
} }
if let Some(first) = first { if let Some(first) = first {
sum += 10 * parse_string_digit(first)? + parse_string_digit(last)?; sum += 10 * first + last;
} }
} }