69 lines
2.3 KiB
Rust
69 lines
2.3 KiB
Rust
use crate::Solution;
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use std::fs;
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use std::process;
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use regex::Regex;
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pub fn run_day_3() -> Solution {
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let file = fs::read_to_string("./inputs/day3.txt").expect("Unable to parse file");
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let re = Regex::new("mul\\((\\d{1,3}),(\\d{1,3})\\)").unwrap();
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let mut part1_sum = 0;
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for mul in re.captures_iter(&file) {
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// Multiply the second and the third matches.
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let num1: &u32 = &mul[1].parse().expect("Conversion failed");
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let num2: &u32 = &mul[2].parse().expect("Conversion failed");
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let total = num1 * num2;
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part1_sum += total;
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}
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// get all matches of do and their index
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// get all matches of dont and their index
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let mut part2_sum = 0;
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let dont_regex = Regex::new("don't\\(\\)").unwrap();
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let do_regex = Regex::new("do\\(\\)").unwrap();
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let donts: Vec<u64> = dont_regex.find_iter(&file).map(|m| m.start() as u64).collect();
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let dos: Vec<u64> = do_regex.find_iter(&file).map(|m| m.start() as u64).collect();
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for mul in re.captures_iter(&file) {
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let start: usize = mul.get(0).unwrap().start();
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// get the closest number, that is lower than the start value
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let mut closest_dont = 0;
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for i in (0..start).rev() {
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let mut index = i as u64;
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if donts.contains(&index) {
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closest_dont = index;
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break;
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}
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}
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let mut closest_do = 0;
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for i in (0..start).rev() {
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let mut index = i as u64;
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if dos.contains(&index) {
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closest_do = index;
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break;
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}
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}
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if closest_do > closest_dont {
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let num1: &u32 = &mul[1].parse().expect("Conversion failed");
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let num2: &u32 = &mul[2].parse().expect("Conversion failed");
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let total = num1 * num2;
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part2_sum += total;
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}
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if closest_do == 0 && closest_dont == 0 {
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let num1: &u32 = &mul[1].parse().expect("Conversion failed");
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let num2: &u32 = &mul[2].parse().expect("Conversion failed");
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let total = num1 * num2;
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part2_sum += total;
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}
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}
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// Final solutions here.
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let solution = Solution {
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day: 3,
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answer_1: part1_sum.to_string(),
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answer_2: part2_sum.to_string(),
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};
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solution
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}
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