advent_of_code_2022/aoc_13b/src/main.rs

use std::fs::File;
use std::io::{self, BufRead};
use std::path::Path;
use std::cmp::Ordering;

#[derive(Debug)]
enum Elem {
    Number(u8),
    List(Vec<Elem>),
}

use crate::Elem::{Number, List};

// I modified my input because the only 2 digits number was 10
// I replaced all 10s with ':' so that I can parse more easely

fn parse_line(line: &str, mut ind: usize) -> (Elem, usize) {
    let mut elems: Vec<Elem> = vec![];
    let mut len = 0;
    while ind < line.len() {
        let a = line[ind..ind+1].chars().next().unwrap();
        match a {
            '[' => { // Creer une List, la push sur le vecteur en cours

                println!("Entering sublist from index {} to {}", ind, ind+1);
                let (a, b) = parse_line(line, ind+1);
                println!("Sublist len was {}, Left sublist, now at index {}", b, ind+b);
                ind += b;
                len += b;
                elems.push(a);
            },
            ']' => {
                println!("Returning list with index {}", ind);
                return (List(elems), len + 1);
            } // Remonter le vecteur en cours de 1,
            '0'..=':' => {
                    println!("Pushing {}", a as u8 - b'0');
                    elems.push(Number(a as u8 - b'0')); // Creer un nombre, le push sur le vecteur en cours
            },
            _ => (),
        };
        ind += 1;
        len += 1;
    }
    unreachable!("parse_line end of function");
    //println!("unreachable !!!! UNREACHABLE");
    //(List(elems), len)
}

fn compare(lhs: &Elem, rhs: &Elem) -> Ordering {
    let mut lhs_v = &vec![];
    let mut rhs_v = &vec![];

    if let List(a) = lhs {
        lhs_v = a;
    }
    if let List(a) = rhs {
        rhs_v = a;
    }

    println!("[ start list");
    for i in 0..lhs_v.len() {
        if i >= rhs_v.len() {
            println!("Right side ran out of items, so inputs are NOT in the right order");
            return Ordering::Greater;
        }
        match (&lhs_v[i], &rhs_v[i]) {
            (List(_), List(_)) => {
                let c = compare(&lhs_v[i], &rhs_v[i]);
                if c != Ordering::Equal {
                    return c;
                }
            },
            (List(_), Number(b)) => {
                println!("Mixed types; convert right to [{}] and retry comparison", b);
                let c = compare(&lhs_v[i], &List(vec![Number(*b)]));
                if c != Ordering::Equal {
                    return c;
                }
            },
            (Number(a), List(_)) => {
                println!("Mixed types; convert left to [{}] and retry comparison", a);
                let c = compare(&List(vec![Number(*a)]), &rhs_v[i]);
                if c != Ordering::Equal {
                    return c;
                }
            },
            (Number(a), Number(b)) => {
                println!("Compare {} vs {}", a, b);
                if a < b {
                    println!("Left side is smaller, so input are in the right order");
                    return Ordering::Less;
                }
                if a > b {
                    println!("Right side is smaller, so input are NOT in the right order");
                    return Ordering::Greater;
                }
            }
        }
    }
    if rhs_v.len() > lhs_v.len() {
        println!("Left side ran out of items, so inputs are in the right order");
        return Ordering::Less;
    }
    println!("end list ]");
    Ordering::Equal
}

fn main() {
    let file_path = String::from("../aoc_13a/input");
    println!("In file {}", file_path);
    let mut data: Vec<Elem> = vec![];

    if let Ok(lines) = read_lines(file_path) {
        // Consumes the iterator, returns an (Optional) String
        for (i, line) in lines.enumerate() {
            if let Ok(ip) = line {
                match i % 3 {
                    0..=1 => data.push(parse_line(&ip, 1).0),
                    _ => (),
                }
            }
        }
    }

    data.push(List(vec![List(vec![Number(2)])]));
    data.push(List(vec![List(vec![Number(6)])]));
    data.sort_by(|a, b| compare(a, b));

    let mut a = None;
    let mut b = None;
    for i in 0..data.len() {
        if compare(&data[i], &List(vec![List(vec![Number(2)])])) == Ordering::Equal {
            a = Some(i + 1);
        }
        if compare(&data[i], &List(vec![List(vec![Number(6)])])) == Ordering::Equal {
            b = Some(i + 1);
        }
    }
    let a = a.unwrap();
    let b = b.unwrap();
    println!("{} {} {}", a, b, a * b);
    //println!("{:?}", data);
}

fn read_lines<P>(filename: P) -> io::Result<io::Lines<io::BufReader<File>>>
where P: AsRef<Path>, {
    let file = File::open(filename)?;
    Ok(io::BufReader::new(file).lines())
}