110 lines
3.0 KiB
Rust
110 lines
3.0 KiB
Rust
use std::fs::File;
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use std::io::{self, BufRead};
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use std::path::Path;
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use std::cmp::Ordering;
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#[derive(Debug)]
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enum Elem {
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Number(u8),
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List(Vec<Elem>),
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}
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use crate::Elem::{Number, List};
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// I modified my input because the only 2 digits number was 10
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// I replaced all 10s with ':' so that I can parse more easely
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fn parse_line(line: &str, index: usize) -> (Elem, usize) {
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let mut list: Vec<Elem> = vec![];
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let mut len = 0;
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while index + len < line.len() {
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let c = line.as_bytes()[index + len];
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len += 1;
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match c {
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b'[' => {
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let (sublist, sublist_len) = parse_line(line, index + len);
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len += sublist_len;
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list.push(sublist);
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},
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b']' => return (List(list), len),
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b'0'..=b':' => list.push(Number(c - b'0')),
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_ => (),
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};
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}
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unreachable!("parse_line end of function");
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}
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fn compare(lhs: &Elem, rhs: &Elem) -> Ordering {
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let mut lhs_v = &vec![];
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let mut rhs_v = &vec![];
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if let List(a) = lhs {
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lhs_v = a;
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}
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if let List(a) = rhs {
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rhs_v = a;
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}
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for i in 0..lhs_v.len() {
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if i >= rhs_v.len() {
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return Ordering::Greater;
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}
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let compare_result = match (&lhs_v[i], &rhs_v[i]) {
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(List(_), List(_)) => compare(&lhs_v[i], &rhs_v[i]),
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(List(_), Number(b)) => compare(&lhs_v[i], &List(vec![Number(*b)])),
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(Number(a), List(_)) => compare(&List(vec![Number(*a)]), &rhs_v[i]),
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(Number(a), Number(b)) => a.cmp(b),
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};
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if compare_result != Ordering::Equal {
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return compare_result;
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}
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}
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if rhs_v.len() > lhs_v.len() {
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return Ordering::Less;
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}
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Ordering::Equal
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}
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fn main() {
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let file_path = String::from("../aoc_13a/input");
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println!("In file {}", file_path);
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let mut data: Vec<Elem> = vec![];
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if let Ok(lines) = read_lines(file_path) {
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// Consumes the iterator, returns an (Optional) String
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for (i, line) in lines.enumerate() {
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if let Ok(ip) = line {
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match i % 3 {
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0..=1 => data.push(parse_line(&ip, 1).0),
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_ => (),
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}
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}
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}
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}
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data.push(List(vec![List(vec![Number(2)])]));
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data.push(List(vec![List(vec![Number(6)])]));
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data.sort_by(|a, b| compare(a, b));
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let mut a = None;
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let mut b = None;
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for i in 0..data.len() {
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if compare(&data[i], &List(vec![List(vec![Number(2)])])) == Ordering::Equal {
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a = Some(i + 1);
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}
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if compare(&data[i], &List(vec![List(vec![Number(6)])])) == Ordering::Equal {
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b = Some(i + 1);
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}
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}
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let a = a.unwrap();
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let b = b.unwrap();
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println!("{} {} {}", a, b, a * b);
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}
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fn read_lines<P>(filename: P) -> io::Result<io::Lines<io::BufReader<File>>>
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where P: AsRef<Path>, {
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let file = File::open(filename)?;
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Ok(io::BufReader::new(file).lines())
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}
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