AdvenOfCode2022/src/prob3/mod.rs

use std::collections::HashSet;

fn character_to_code(input: i32) -> i32 {
    if input >= ('a' as i32) {
        input - 96
    } else {
        input - 38
    }
}

pub fn solve_part1(file_path: &str) -> i32 {
    let binding =
        std::fs::read_to_string(file_path).expect("Please provide a text file as an argument.");
    binding
        .lines()
        .collect::<Vec<&str>>()
        .iter()
        .map(|item: &&str| {
            let (first, last) = item.split_at(item.len() / 2);
            let second = last.chars().collect::<HashSet<char>>();
            let intersection = first.chars().collect::<HashSet<char>>();
            let character = *intersection
                .intersection(&second)
                .next()
                .unwrap_or(&(0 as char)) as i32;
            character_to_code(character)
        })
        .collect::<Vec<i32>>()
        .iter()
        .sum::<i32>()
}

pub fn solve_part2(file_path: &str) -> i32 {
    let binding =
        std::fs::read_to_string(file_path).expect("Please provide a text file as an argument.");
    let mut iter = binding.lines();
    binding
        .lines()
        .step_by(3)
        .collect::<Vec<&str>>()
        .iter()
        .map(|_item| {
            let common_letter = {
                let first = &iter
                    .next()
                    .expect("Expected a string, not nothing.")
                    .chars()
                    .collect::<HashSet<char>>()
                    & &iter
                        .next()
                        .expect("Expected a string, not nothing.")
                        .chars()
                        .collect::<HashSet<char>>();
                &first
                    & &iter
                        .next()
                        .expect("Expected a string, not nothing.")
                        .chars()
                        .collect::<HashSet<char>>()
            };
            if !common_letter.is_empty() && common_letter.len() > 1 {
                panic!("Anormal behavior. Must have only 1 element in {common_letter:?}");
            } else {
                let unique_letter = *common_letter
                    .iter()
                    .last()
                    .expect("Impossible to have this message else Rust has a problem...")
                    as i32;
                character_to_code(unique_letter)
            }
        })
        .collect::<Vec<i32>>()
        .iter()
        .sum::<i32>()
}