Advent of Code 2022

I use this to learn Rust.

I'll see how far I get in terms of the puzzles themselves. I'll try to write some key learnings/struggles for each day hoping that once I progressed a bit I'll look at the first days and think: "Well, of course! Noob!"

Since I use this as a learning experience, solutions might be over-engineered and use naive algorithms at the same time 😁

Day 1

Getting used to the basic syntax and the basics of tooling

Day 2

Struggling with memory management.

fn read_input(file_path: &str) -> Vec<String> {
    let contents = fs::read_to_string(file_path)
        .expect("File not found");

    let lines = contents.split("\r\n");

    let mut r: Vec<String> = vec![];
    for line in lines {
        r.push(String::from(line));
    }

    return r;
}

The only way I found to abstract away the basic reading of the input files is to copy the lines into a new vector creating new Strings from the Slices the split method creates since the slices reference data in the local variable contents that will be out of scope by the end of the function.

Day 3

Made a local crate. Works great, but no code completion in the IDE.

Day 4

I have the feeling I still do too much work for extracting data from strings :-(

I use this to split a string like 12-24,54-67 into its four parts. Will look at regular expressions in Rust.

fn get_ranges(inp: &String) -> Vec<Range> {
    let ranges = inp.split(",").collect::<Vec<&str>>();

    let mut result: Vec<Range> = vec![];

    if ranges.len() == 2 {
        let mut parts = ranges[0].split("-").collect::<Vec<&str>>();

        if parts.len() == 2 {
            result.push(Range { a: parts[0].parse().unwrap(), b: parts[1].parse().unwrap()})
        }

        parts = ranges[1].split("-").collect::<Vec<&str>>();

        if parts.len() == 2 {
            result.push(Range { a: parts[0].parse().unwrap(), b: parts[1].parse().unwrap()})
        }
    }

    result
}

What I like so far

• Error-Messages and documentation are both really helpful!
• Side-By-Side-Testing is quite seamless

Day 5

Parsing the input was messy.

I had lots of trouble with borrowing and stuff.

I use a Vec<Vec<char>> to represent the stack. When I parse the input file top to bottom, the stacks will be in reverse order when simply pushing into them. I fixed that with insert(0, crate). But at first I wanted to simply reverse all the stack-vectors.

    fn main() {
    
        /* ... */
    
        for mut stack in stacks {
            stack.reverse()
        }

        state[0].pop();     // Cannot mutate as the implicit call to into_iter() in the loop already borrowed
    }

So I tried to use a slice

    fn main() {
    
        /* ... */
    
        for mut stack in stacks[0..] {
            stack.reverse() // `stack` is a `&` reference, so the data it refers to cannot be borrowed as mutable
        }

        state[0].pop(); 
    }

🤷‍♂️

Day 6-9

I am still using mostly the basics of the language. The standard-library is quite big. The docs for it are sometimes not that easy to grasp. Sometimes need myself to force more to properly read the error messages. They almost always contain very helpful information.

Day 10

I really like the traits concept. Mostly use it for Display/Debug to print out info when figuring out why my algorithm doesn't do what I think it should be doing.

Day 11

This was hard, because for the longest time I tried to manipulate a Vector I'm iterating over. I really need to learn the collection types and their features.

License

See here