AdventOfCode/y2024/src/days/d3.rs

90 lines
2.5 KiB
Rust

use regex::Regex;
pub fn process_part1(input: &str) -> i32 {
input
.lines()
.map(extract_mul_pairs)
.map(|pairs| pairs.iter().map(|(a, b)| a * b).sum::<i32>())
.sum()
}
// Could use this regex but wouldn't know how to solve part 2
// /mul\([0-9]{1,3},[0-9]{1,3}\)/g
// /don't\(\).*do\(\)/g would select anything between first don't() and last do()
// not sure how to fix, invert and combine this
fn extract_mul_pairs(line: &str) -> Vec<(i32, i32)> {
let reg = Regex::new(r"mul\([0-9]{1,3},[0-9]{1,3}\)").unwrap();
reg.find_iter(line)
.map(|m| {
let match_str = m.as_str();
let (a, b) = match_str[4..match_str.len() - 1].split_once(",").unwrap();
let a = a.parse::<i32>().unwrap();
let b = b.parse::<i32>().unwrap();
(a, b)
})
.collect::<Vec<(i32, i32)>>()
}
fn remove_donts(line: &str) -> String {
let mut new_line = line.to_string();
loop {
println!("len {}", line.len());
let mut end_range = new_line.len() - 1;
if let Some(dont_idx) = new_line.find("don't()") {
if let Some(do_idx) = new_line.find("do()") {
if dont_idx < do_idx {
end_range = do_idx + 4;
}
}
println!("dont {dont_idx} to {end_range}");
new_line.replace_range(dont_idx..end_range, "");
} else {
return new_line;
}
}
}
pub fn process_part2(input: &str) -> i32 {
input
.lines()
.map(|line| {
let line = remove_donts(line);
extract_mul_pairs(&line)
})
.map(|pairs| pairs.iter().map(|(a, b)| a * b).sum::<i32>())
.sum()
}
#[cfg(test)]
mod tests {
use std::fs;
use super::*;
const INPUT: &str =
"xmul(2,4)%&mul[3,7]!@^do_not_mul(5,5)+mul(32,64]then(mul(11,8)mul(8,5))mul( 1, 3)";
const INPUT_2: &str =
"xmul(2,4)&mul[3,7]!^don't()_mul(5,5)+mul(32,64](mul(11,8)undo()?mul(8,5))";
#[test]
fn part1() {
let result = process_part1(INPUT);
assert_eq!(result, 161);
}
#[test]
fn res1() {
let root = env!("CARGO_MANIFEST_DIR");
let content = fs::read_to_string(format!("{root}/resources/3_input.txt")).unwrap();
let result = process_part1(&content);
assert_eq!(result, 183788984);
}
#[test]
fn part2() {
let result = process_part2(INPUT_2);
assert_eq!(result, 48);
}
}