129 lines
3.7 KiB
Rust
129 lines
3.7 KiB
Rust
use regex::Regex;
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pub fn process_part1(input: &str) -> i32 {
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input
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.lines()
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.map(extract_mul_pairs)
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.map(|pairs| pairs.iter().map(|(a, b)| a * b).sum::<i32>())
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.sum()
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}
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// Could use this regex but wouldn't know how to solve part 2
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// /mul\([0-9]{1,3},[0-9]{1,3}\)/g
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// /don't\(\).*do\(\)/g would select anything between first don't() and last do()
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// not sure how to fix, invert and combine this
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fn extract_mul_pairs(line: &str) -> Vec<(i32, i32)> {
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let reg = Regex::new(r"mul\([0-9]{1,3},[0-9]{1,3}\)").unwrap();
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reg.find_iter(line)
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.map(|m| {
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let match_str = m.as_str();
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let (a, b) = match_str[4..match_str.len() - 1].split_once(",").unwrap();
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let a = a.parse::<i32>().unwrap();
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let b = b.parse::<i32>().unwrap();
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(a, b)
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})
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.collect::<Vec<(i32, i32)>>()
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}
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fn extract_mul_pairs_dont(line: &str) -> Vec<(i32, i32)> {
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let mut pairs = Vec::new();
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for (idx, _) in line.match_indices("mul(") {
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if let Some(dont_func) = line[..idx].rfind("don't()") {
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if let Some(do_func) = line[..idx].rfind("do()") {
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if do_func < dont_func {
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continue;
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}
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} else {
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continue;
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}
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}
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let mut invalid = false;
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let mut comma_pos = 0;
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let mut pair = ("".to_string(), "".to_string());
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// max length of parenthesis == 9
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for paren_idx in 0..9 {
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let paren_content = match line.as_bytes().get(idx + 4 + paren_idx) {
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Some(content) => *content as char,
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None => {
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invalid = true;
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break;
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}
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};
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if paren_content == ')' {
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if comma_pos == 0 {
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invalid = true;
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}
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break;
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}
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if paren_content == ',' {
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comma_pos = paren_idx;
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continue;
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}
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if !paren_content.is_ascii_digit() {
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invalid = true;
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break;
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}
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if comma_pos == 0 {
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pair.0.push(paren_content);
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} else {
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pair.1.push(paren_content);
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}
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}
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if !invalid {
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let a = pair.0.parse::<i32>().unwrap();
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let b = pair.1.parse::<i32>().unwrap();
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pairs.push((a, b));
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}
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}
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pairs
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}
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pub fn process_part2(input: &str) -> i32 {
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let input = input.lines().collect::<Vec<&str>>().join("");
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extract_mul_pairs_dont(&input)
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.into_iter()
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.map(|(a, b)| a * b)
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.sum()
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}
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#[cfg(test)]
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mod tests {
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use std::fs;
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use super::*;
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const INPUT: &str =
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"xmul(2,4)%&mul[3,7]!@^do_not_mul(5,5)+mul(32,64]then(mul(11,8)mul(8,5))mul( 1, 3)";
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const INPUT_2: &str =
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"xmul(2,4)&mul[3,7]!^don't()_mul(5,5)+mul(32,64](mul(11,8)undo()?mul(8,5))";
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#[test]
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fn part1() {
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let result = process_part1(INPUT);
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assert_eq!(result, 161);
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}
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#[test]
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fn res1() {
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let root = env!("CARGO_MANIFEST_DIR");
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let content = fs::read_to_string(format!("{root}/resources/3_input.txt")).unwrap();
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let result = process_part1(&content);
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assert_eq!(result, 183788984);
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}
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#[test]
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fn part2() {
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let result = process_part2(INPUT_2);
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assert_eq!(result, 48);
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}
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#[test]
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fn res2() {
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let root = env!("CARGO_MANIFEST_DIR");
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let content = fs::read_to_string(format!("{root}/resources/3_input.txt")).unwrap();
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let result = process_part2(&content);
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assert_eq!(result, 62098619);
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}
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}
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